From a099063448c5b35cfdefc9df54b2d409d76be188 Mon Sep 17 00:00:00 2001
From: apostolof <apotwohd@gmail.com>
Date: Sun, 25 Apr 2021 12:26:46 +0300
Subject: [PATCH] Squash commit

---
 .gitignore              |   3 +
 cilk/bitonic.c          | 292 +++++++++++++++++++++++++++++
 noOpt/bitonicCilk.c     | 274 ++++++++++++++++++++++++++++
 noOpt/bitonicOpenMP.c   | 285 +++++++++++++++++++++++++++++
 noOpt/bitonicPthreads.c | 380 ++++++++++++++++++++++++++++++++++++++
 openMP/bitonic.c        | 304 +++++++++++++++++++++++++++++++
 pthreads/bitonic.c      | 395 ++++++++++++++++++++++++++++++++++++++++
 pthreads/bitonicImp.c   | 249 +++++++++++++++++++++++++
 pthreads/bitonicRec.c   | 320 ++++++++++++++++++++++++++++++++
 qsort/qsort.c           | 110 +++++++++++
 seq/bitonic.c           | 215 ++++++++++++++++++++++
 11 files changed, 2827 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 cilk/bitonic.c
 create mode 100644 noOpt/bitonicCilk.c
 create mode 100644 noOpt/bitonicOpenMP.c
 create mode 100644 noOpt/bitonicPthreads.c
 create mode 100644 openMP/bitonic.c
 create mode 100644 pthreads/bitonic.c
 create mode 100644 pthreads/bitonicImp.c
 create mode 100644 pthreads/bitonicRec.c
 create mode 100644 qsort/qsort.c
 create mode 100644 seq/bitonic.c

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b61379f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.out
+.idea
+*.iml
diff --git a/cilk/bitonic.c b/cilk/bitonic.c
new file mode 100644
index 0000000..069352e
--- /dev/null
+++ b/cilk/bitonic.c
@@ -0,0 +1,292 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
+#include <cilk/cilk.h>
+#include <cilk/cilk_api.h>
+
+typedef enum { false, true } bool;
+struct timeval startwtime, endwtime;
+double seq_time;
+
+int threads; //number of threads
+int N; // data array size
+int *a; // data array to be sorted
+unsigned randSeed; //seed array initialisation
+bool sortPass; //flag showing whether the test passed or not
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+//cilk for grainsize
+const int REC_BITONIC_MERGE_PARALLEL_GRAINSIZE = 1 << 14;
+//min lenght of an array to be sorted by bitonicMerge in parallel manner
+const int REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN = (1 << 12) - 1;
+//min lenght of an array to be merged by bitonicMerge in parallel manner
+const int REC_BITONIC_MERGE_PARALLEL_CALL_MIN = (1 << 8) - 1;
+//min lenght of an array to be sorted in parallel manner
+const int REC_BITONIC_SORT_PARALLEL_MIN = (1 << 22) + 1;
+
+void getArgs(int argc, char** argv);
+void init(void);
+void print(void);
+void sort(void);
+void test(void);
+void qSortTest(void);
+void exchange(int i, int j);
+void compare(int i, int j, int dir);
+void bitonicMerge(int lo, int cnt, int dir);
+void recBitonicSort(int lo, int cnt, int dir);
+void impBitonicSort(void);
+int qSortAscendingCompFuncWithTest (const void * a, const void * b);
+int qSortAscending (const void * a, const void * b);
+int qSortDescending (const void * a, const void * b);
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+	getArgs(argc, argv);
+	a = (int *) malloc(N * sizeof(int));
+	randSeed = (unsigned) time(NULL);
+
+	if (0!= __cilkrts_set_param("nworkers","0" + threads)){
+		printf("Failed to set worker count\n");
+		exit(1);
+	}
+
+	//Sorts using the qSort algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	qsort(a, N, sizeof(int), qSortAscending);
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("qSort wall clock time = %f\n\n", seq_time);
+
+	//Sorts using the imperative bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	impBitonicSort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("Imperative wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	//Sorts using the recursive bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	sort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("\nRecursive wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	free(a);
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+void getArgs(int argc, char** argv){
+	if (argc != 3) {
+		printf("Usage: %s p q\nwhere:\n\tP=2^p is the the number of threads(power of two)\n\tN=2^q is problem size (power of two)\n", 
+			argv[0]);
+		exit(1);
+	}
+	threads = 1<<atoi(argv[1]);
+	N = 1<<atoi(argv[2]);
+}
+
+/** procedure test() : verify sort results **/
+void test() {
+	int pass = 1;
+	int i;
+	for (i = 1; i < N; i++) {
+		pass &= (a[i-1] <= a[i]);
+	}
+	printf("\tTEST\t\t%s\n",(pass) ? "PASSed" : "FAILed");
+}
+
+/** procedure qSortTest() : verify sort results using qsort method **/
+void qSortTest(){
+	sortPass = true;
+	qsort(a, N, sizeof(int), qSortAscendingCompFuncWithTest);
+	printf("\tQSORT TEST\t%s\n",(sortPass) ? "PASSed" : "FAILed");
+}
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+	srand(randSeed);
+	int i;
+	for (i = 0; i < N; i++) {
+		a[i] = rand() % N; // (N - i);
+	}
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+	int i;
+	for (i = 0; i < N; i++) {
+		printf("%d\n", a[i]);
+	}
+	printf("\n");
+}
+
+/** INLINE procedure exchange() : pair swap **/
+inline void exchange(int i, int j) {
+	int t;
+	t = a[i];
+	a[i] = a[j];
+	a[j] = t;
+}
+
+/** procedure compare() 
+   The parameter dir indicates the sorting direction, ASCENDING 
+   or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+   then a[i] and a[j] are interchanged.
+**/
+inline void compare(int i, int j, int dir) {
+	if (dir==(a[i]>a[j])) 
+		exchange(i,j);
+}
+
+/** Procedure bitonicMerge() 
+   It recursively sorts a bitonic sequence in ascending order, 
+   if dir = ASCENDING, and in descending order otherwise. 
+   The sequence to be sorted starts at index position lo,
+   the parameter cbt is the number of elements to be sorted. 
+ **/
+void bitonicMerge(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		int k=cnt/2;
+		int i;
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN){
+			#pragma cilk_grainsize = 8192
+			cilk_for (i=lo; i<lo+k; i++){
+				compare(i, i+k, dir);
+			}
+		} else {
+			for (i=lo; i<lo+k; i++){
+				compare(i, i+k, dir);
+			}
+		}
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_CALL_MIN){
+			cilk_spawn bitonicMerge(lo, k, dir);
+			cilk_spawn bitonicMerge(lo+k, k, dir);
+			cilk_sync;
+		} else{
+			bitonicMerge(lo, k, dir);
+			bitonicMerge(lo+k, k, dir);
+		}
+	}
+}
+
+/** function recBitonicSort() 
+    first produces a bitonic sequence by recursively sorting 
+    its two halves in opposite sorting orders, and then
+    calls bitonicMerge to make them in the same order 
+ **/
+void recBitonicSort(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		if (cnt < REC_BITONIC_SORT_PARALLEL_MIN){
+			qsort(a+lo, cnt, sizeof(int), (dir == 1 ? qSortAscending : qSortDescending));
+			return;
+		}
+		int k=cnt/2;
+		cilk_spawn recBitonicSort(lo, k, ASCENDING);
+		cilk_spawn recBitonicSort(lo+k, k, DESCENDING);
+		cilk_sync;
+		bitonicMerge(lo, cnt, dir);
+	}
+}
+
+/** function sort() 
+   Caller of recBitonicSort for sorting the entire array of length N 
+   in ASCENDING order
+ **/
+void sort() {
+	recBitonicSort(0, N, ASCENDING);
+}
+
+/*
+  imperative version of bitonic sort
+*/
+void impBitonicSort() {
+	int i,j,k;
+
+	for (k=2; k<=N; k+=k) {
+		for (j=k>>1; j>0; j=j>>1) {
+			#pragma cilk_grainsize = N/4
+			cilk_for (i=0; i<N; i++) {
+				int ij=i^j;
+				if ((ij)>i) {
+					if ((i&k)==0 && a[i] > a[ij]) 
+						exchange(i,ij);
+					if ((i&k)!=0 && a[i] < a[ij])
+						exchange(i,ij);
+				}
+			}
+		}
+	}
+}
+
+/** function used by qsort for comparing as well as testing **/
+int qSortAscendingCompFuncWithTest (const void * a, const void * b) {
+	int result = ( *(int*)a - *(int*)b );
+	if (result > 0){
+		sortPass = false;
+	}
+	return result;
+}
+
+/** function used by qsort for comparing **/
+int qSortAscending (const void * a, const void * b) {
+	return ( *(int*)a - *(int*)b );
+}
+
+/** function used by qsort for comparing **/
+int qSortDescending (const void * a, const void * b) {
+	return ( *(int*)b - *(int*)a );
+}
\ No newline at end of file
diff --git a/noOpt/bitonicCilk.c b/noOpt/bitonicCilk.c
new file mode 100644
index 0000000..df26b07
--- /dev/null
+++ b/noOpt/bitonicCilk.c
@@ -0,0 +1,274 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
+#include <cilk/cilk.h>
+#include <cilk/cilk_api.h>
+
+typedef enum { false, true } bool;
+struct timeval startwtime, endwtime;
+double seq_time;
+
+int threads; //number of threads
+int N; // data array size
+int *a; // data array to be sorted
+unsigned randSeed; //seed array initialisation
+bool sortPass; //flag showing whether the test passed or not
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+//cilk for grainsize
+const int REC_BITONIC_MERGE_PARALLEL_GRAINSIZE = 1 << 14;
+//min lenght of an array to be sorted by bitonicMerge in parallel manner
+const int REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN = (1 << 12) - 1;
+//min lenght of an array to be merged by bitonicMerge in parallel manner
+const int REC_BITONIC_MERGE_PARALLEL_CALL_MIN = (1 << 8) - 1;
+//min lenght of an array to be sorted in parallel manner
+const int REC_BITONIC_SORT_PARALLEL_MIN = (1 << 22) + 1;
+
+void getArgs(int argc, char** argv);
+void init(void);
+void print(void);
+void sort(void);
+void test(void);
+void qSortTest(void);
+void exchange(int i, int j);
+void compare(int i, int j, int dir);
+void bitonicMerge(int lo, int cnt, int dir);
+void recBitonicSort(int lo, int cnt, int dir);
+void impBitonicSort(void);
+int qSortAscendingCompFuncWithTest (const void * a, const void * b);
+int qSortAscending (const void * a, const void * b);
+int qSortDescending (const void * a, const void * b);
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+	getArgs(argc, argv);
+	a = (int *) malloc(N * sizeof(int));
+	randSeed = (unsigned) time(NULL);
+
+	if (0!= __cilkrts_set_param("nworkers","0" + threads)){
+		printf("Failed to set worker count\n");
+		exit(1);
+	}
+
+	//Sorts using the qSort algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	qsort(a, N, sizeof(int), qSortAscending);
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("qSort wall clock time = %f\n\n", seq_time);
+
+	//Sorts using the recursive bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	sort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("\nRecursive wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	free(a);
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+void getArgs(int argc, char** argv){
+	if (argc != 3) {
+		printf("Usage: %s p q\nwhere:\n\tP=2^p is the the number of threads(power of two)\n\tN=2^q is problem size (power of two)\n", 
+			argv[0]);
+		exit(1);
+	}
+	threads = 1<<atoi(argv[1]);
+	N = 1<<atoi(argv[2]);
+}
+
+/** procedure test() : verify sort results **/
+void test() {
+	int pass = 1;
+	int i;
+	for (i = 1; i < N; i++) {
+		pass &= (a[i-1] <= a[i]);
+	}
+	printf("\tTEST\t\t%s\n",(pass) ? "PASSed" : "FAILed");
+}
+
+/** procedure qSortTest() : verify sort results using qsort method **/
+void qSortTest(){
+	sortPass = true;
+	qsort(a, N, sizeof(int), qSortAscendingCompFuncWithTest);
+	printf("\tQSORT TEST\t%s\n",(sortPass) ? "PASSed" : "FAILed");
+}
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+	srand(randSeed);
+	int i;
+	for (i = 0; i < N; i++) {
+		a[i] = rand() % N; // (N - i);
+	}
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+	int i;
+	for (i = 0; i < N; i++) {
+		printf("%d\n", a[i]);
+	}
+	printf("\n");
+}
+
+/** INLINE procedure exchange() : pair swap **/
+inline void exchange(int i, int j) {
+	int t;
+	t = a[i];
+	a[i] = a[j];
+	a[j] = t;
+}
+
+/** procedure compare() 
+   The parameter dir indicates the sorting direction, ASCENDING 
+   or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+   then a[i] and a[j] are interchanged.
+**/
+inline void compare(int i, int j, int dir) {
+	if (dir==(a[i]>a[j])) 
+		exchange(i,j);
+}
+
+/** Procedure bitonicMerge() 
+   It recursively sorts a bitonic sequence in ascending order, 
+   if dir = ASCENDING, and in descending order otherwise. 
+   The sequence to be sorted starts at index position lo,
+   the parameter cbt is the number of elements to be sorted. 
+ **/
+void bitonicMerge(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		int k=cnt/2;
+		int i;
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN){
+			#pragma cilk_grainsize = 8192
+			cilk_for (i=lo; i<lo+k; i++){
+				compare(i, i+k, dir);
+			}
+		} else {
+			for (i=lo; i<lo+k; i++){
+				compare(i, i+k, dir);
+			}
+		}
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_CALL_MIN){
+			cilk_spawn bitonicMerge(lo, k, dir);
+			cilk_spawn bitonicMerge(lo+k, k, dir);
+			cilk_sync;
+		} else{
+			bitonicMerge(lo, k, dir);
+			bitonicMerge(lo+k, k, dir);
+		}
+	}
+}
+
+/** function recBitonicSort() 
+    first produces a bitonic sequence by recursively sorting 
+    its two halves in opposite sorting orders, and then
+    calls bitonicMerge to make them in the same order 
+ **/
+void recBitonicSort(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		
+		int k=cnt/2;
+		cilk_spawn recBitonicSort(lo, k, ASCENDING);
+		cilk_spawn recBitonicSort(lo+k, k, DESCENDING);
+		cilk_sync;
+		bitonicMerge(lo, cnt, dir);
+	}
+}
+
+/** function sort() 
+   Caller of recBitonicSort for sorting the entire array of length N 
+   in ASCENDING order
+ **/
+void sort() {
+	recBitonicSort(0, N, ASCENDING);
+}
+
+/*
+  imperative version of bitonic sort
+*/
+void impBitonicSort() {
+	int i,j,k;
+
+	for (k=2; k<=N; k+=k) {
+		for (j=k>>1; j>0; j=j>>1) {
+			#pragma cilk_grainsize = N/4
+			cilk_for (i=0; i<N; i++) {
+				int ij=i^j;
+				if ((ij)>i) {
+					if ((i&k)==0 && a[i] > a[ij]) 
+						exchange(i,ij);
+					if ((i&k)!=0 && a[i] < a[ij])
+						exchange(i,ij);
+				}
+			}
+		}
+	}
+}
+
+/** function used by qsort for comparing as well as testing **/
+int qSortAscendingCompFuncWithTest (const void * a, const void * b) {
+	int result = ( *(int*)a - *(int*)b );
+	if (result > 0){
+		sortPass = false;
+	}
+	return result;
+}
+
+/** function used by qsort for comparing **/
+int qSortAscending (const void * a, const void * b) {
+	return ( *(int*)a - *(int*)b );
+}
+
+/** function used by qsort for comparing **/
+int qSortDescending (const void * a, const void * b) {
+	return ( *(int*)b - *(int*)a );
+}
\ No newline at end of file
diff --git a/noOpt/bitonicOpenMP.c b/noOpt/bitonicOpenMP.c
new file mode 100644
index 0000000..e31ffc9
--- /dev/null
+++ b/noOpt/bitonicOpenMP.c
@@ -0,0 +1,285 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <sys/time.h>
+#include <omp.h>
+
+typedef enum { false, true } bool;
+struct timeval startwtime, endwtime;
+double seq_time;
+
+int threads; //number of threads
+int N;          // data array size
+int *a;         // data array to be sorted
+unsigned randSeed; //seed array initialisation
+bool sortPass; //flag showing whether the test passed or not
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+//min lenght of an array to be sorted by bitonicMerge in parallel manner
+const int REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN = (1 << 12) - 1;
+//min lenght of an array to be merged by bitonicMerge in parallel manner
+const int REC_BITONIC_MERGE_PARALLEL_CALL_MIN = (1 << 8) - 1;
+//min lenght of an array to be sorted in parallel manner
+const int REC_BITONIC_SORT_PARALLEL_MIN = (1 << 22) + 1;
+
+void getArgs(int argc, char** argv);
+void init(void);
+void print(void);
+void sort(void);
+void test(void);
+void qSortTest(void);
+void exchange(int i, int j);
+void compare(int i, int j, int dir);
+void bitonicMerge(int lo, int cnt, int dir);
+void recBitonicSort(int lo, int cnt, int dir);
+void impBitonicSort(void);
+int qSortAscendingCompFuncWithTest (const void * a, const void * b);
+int qSortAscending (const void * a, const void * b);
+int qSortDescending (const void * a, const void * b);
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+	getArgs(argc, argv);
+	a = (int *) malloc(N * sizeof(int));
+	randSeed = (unsigned) time(NULL);
+
+	omp_set_dynamic(0);
+	omp_set_num_threads(threads);
+
+	//Sorts using the qSort algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	qsort(a, N, sizeof(int), qSortAscending);
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("qSort wall clock time = %f\n\n", seq_time);
+
+	//Sorts using the recursive bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	sort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("\nRecursive wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	free(a);
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+void getArgs(int argc, char** argv){
+	if (argc != 3) {
+		printf("Usage: %s p q\nwhere:\n\tP=2^p is the the number of threads(power of two)\n\tN=2^q is problem size (power of two)\n", 
+			argv[0]);
+		exit(1);
+	}
+	threads = 1<<atoi(argv[1]);
+	N = 1<<atoi(argv[2]);
+}
+
+/** procedure test() : verify sort results **/
+void test() {
+	int pass = 1;
+	int i;
+	for (i = 1; i < N; i++) {
+		pass &= (a[i-1] <= a[i]);
+	}
+	printf("\tTEST\t\t%s\n",(pass) ? "PASSed" : "FAILed");
+}
+
+/** procedure qSortTest() : verify sort results using qsort method **/
+void qSortTest(){
+	sortPass = true;
+	qsort(a, N, sizeof(int), qSortAscendingCompFuncWithTest);
+	printf("\tQSORT TEST\t%s\n",(sortPass) ? "PASSed" : "FAILed");
+}
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+	srand(randSeed);
+	int i;
+	for (i = 0; i < N; i++) {
+		a[i] = rand() % N; // (N - i);
+	}
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+	int i;
+	for (i = 0; i < N; i++) {
+		printf("%d\n", a[i]);
+	}
+	printf("\n");
+}
+
+/** INLINE procedure exchange() : pair swap **/
+inline void exchange(int i, int j) {
+	int t;
+	t = a[i];
+	a[i] = a[j];
+	a[j] = t;
+}
+
+/** procedure compare() 
+   The parameter dir indicates the sorting direction, ASCENDING 
+   or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+   then a[i] and a[j] are interchanged.
+**/
+inline void compare(int i, int j, int dir) {
+	if (dir==(a[i]>a[j])) 
+		exchange(i,j);
+}
+
+/** Procedure bitonicMerge() 
+   It recursively sorts a bitonic sequence in ascending order, 
+   if dir = ASCENDING, and in descending order otherwise. 
+   The sequence to be sorted starts at index position lo,
+   the parameter cbt is the number of elements to be sorted. 
+ **/
+void bitonicMerge(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		int k=cnt/2;
+		int i;
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN){
+			#pragma omp parallel for
+			for (i=lo; i<lo+k; i++)
+				compare(i, i+k, dir);
+		} else {
+			for (i=lo; i<lo+k; i++){
+				compare(i, i+k, dir);
+			}
+		}
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_CALL_MIN){
+			#pragma omp parallel sections
+			{
+				#pragma omp section
+				{
+					bitonicMerge(lo, k, dir);
+				}
+				#pragma omp section
+				{
+					bitonicMerge(lo+k, k, dir);
+				}
+			}
+		} else {
+			bitonicMerge(lo, k, dir);
+			bitonicMerge(lo+k, k, dir);
+		}
+	}
+}
+
+/** function recBitonicSort() 
+    first produces a bitonic sequence by recursively sorting 
+    its two halves in opposite sorting orders, and then
+    calls bitonicMerge to make them in the same order 
+ **/
+void recBitonicSort(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		int k=cnt/2;
+		#pragma omp task
+		{
+			recBitonicSort(lo, k, ASCENDING);
+		}
+		
+		#pragma omp task
+		{
+			recBitonicSort(lo+k, k, DESCENDING);
+		}
+		#pragma omp taskwait
+		bitonicMerge(lo, cnt, dir);
+	}
+}
+
+/** function sort() 
+   Caller of recBitonicSort for sorting the entire array of length N 
+   in ASCENDING order
+ **/
+void sort() {
+	#pragma omp parallel num_threads(threads)
+	#pragma omp single nowait
+	recBitonicSort(0, N, ASCENDING);
+}
+
+/*
+  imperative version of bitonic sort
+*/
+void impBitonicSort() {
+
+	int i,j,k;
+
+	for (k=2; k<=N; k=2*k) {
+		for (j=k>>1; j>0; j=j>>1) {
+			#pragma omp parallel for num_threads(threads)
+			for (i=0; i<N; i++) {
+				int ij=i^j;
+				if ((ij)>i) {
+					if ((i&k)==0 && a[i] > a[ij]) 
+						exchange(i,ij);
+					if ((i&k)!=0 && a[i] < a[ij])
+						exchange(i,ij);
+				}
+			}
+		}
+	}
+}
+
+/** function used by qsort for comparing as well as testing **/
+int qSortAscendingCompFuncWithTest (const void * a, const void * b) {
+	int result = ( *(int*)a - *(int*)b );
+	if (result > 0){
+		sortPass = false;
+	}
+	return result;
+}
+
+/** function used by qsort for comparing **/
+int qSortAscending (const void * a, const void * b) {
+	return ( *(int*)a - *(int*)b );
+}
+
+/** function used by qsort for comparing **/
+int qSortDescending (const void * a, const void * b) {
+	return ( *(int*)b - *(int*)a );
+}
\ No newline at end of file
diff --git a/noOpt/bitonicPthreads.c b/noOpt/bitonicPthreads.c
new file mode 100644
index 0000000..a3fa1f4
--- /dev/null
+++ b/noOpt/bitonicPthreads.c
@@ -0,0 +1,380 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
+#include <pthread.h>
+
+typedef enum { false, true } bool;
+struct timeval startwtime, endwtime;
+double seq_time;
+
+int threadsNum; //number of threads
+int N; // data array size
+int *a; // data array to be sorted
+unsigned randSeed; //seed array initialisation
+bool sortPass; //flag showing whether the test passed or not
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+//min lenght of an array to be sorted in parallel manner
+const int REC_BITONIC_SORT_PARALLEL_MIN = (1 << 22) + 1;
+
+//structs for parallel functions
+typedef struct recBitonicSortData{
+	int threadID;
+	int lo;
+	int cnt;
+	int dir;
+} recBitonicSortData;
+
+typedef struct impBitonicSortThreadData{
+	int i;
+	int N;
+	int j;
+	int k;
+} impBitonicSortThreadData;
+
+pthread_t *threads; //array that holds pointers to all threads
+int runningThreads = 0; //number of threads currently running
+pthread_mutex_t runningThreadsMutex = PTHREAD_MUTEX_INITIALIZER;
+
+void getArgs(int argc, char** argv);
+void init(void);
+void print(void);
+void sort(void);
+void test(void);
+void qSortTest(void);
+void exchange(int i, int j);
+void compare(int i, int j, int dir);
+void bitonicMerge(int lo, int cnt, int dir);
+void *recBitonicSort(void *threadArgs);
+void *impBitonicSortThread(void * threadArgs);
+void impBitonicSort(void);
+int qSortAscendingCompFuncWithTest (const void * a, const void * b);
+int qSortAscending (const void * a, const void * b);
+int qSortDescending (const void * a, const void * b);
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+	getArgs(argc, argv);
+	a = (int *) malloc(N * sizeof(int));
+	randSeed = (unsigned) time(NULL);
+
+	//allocates space for an array that holds pointers to all threads
+	threads = (pthread_t *)malloc(sizeof(pthread_t)*threadsNum);
+
+	//Sorts using the qSort algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	qsort(a, N, sizeof(int), qSortAscending);
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("qSort wall clock time = %f\n\n", seq_time);
+
+	//Sorts using the recursive bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	sort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("\nRecursive wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	free(threads);
+	free(a);
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+void getArgs(int argc, char** argv){
+	if (argc != 3) {
+		printf("Usage: %s p q\nwhere:\n\tP=2^p is the the number of threads(power of two)\n\tN=2^q is problem size (power of two)\n", 
+			argv[0]);
+		exit(1);
+	}
+	threadsNum = 1<<atoi(argv[1]);
+	N = 1<<atoi(argv[2]);
+}
+
+/** procedure test() : verify sort results **/
+void test() {
+	int pass = 1;
+	int i;
+	for (i = 1; i < N; i++) {
+		pass &= (a[i-1] <= a[i]);
+	}
+	printf("\tTEST\t\t%s\n",(pass) ? "PASSed" : "FAILed");
+}
+
+/** procedure qSortTest() : verify sort results using qsort method **/
+void qSortTest(){
+	sortPass = true;
+	qsort(a, N, sizeof(int), qSortAscendingCompFuncWithTest);
+	printf("\tQSORT TEST\t%s\n",(sortPass) ? "PASSed" : "FAILed");
+}
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+	srand(randSeed);
+	int i;
+	for (i = 0; i < N; i++) {
+		a[i] = rand() % N; // (N - i);
+	}
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+	int i;
+	for (i = 0; i < N; i++) {
+		printf("%d\n", a[i]);
+	}
+	printf("\n");
+}
+
+/** INLINE procedure exchange() : pair swap **/
+inline void exchange(int i, int j) {
+	int t;
+	t = a[i];
+	a[i] = a[j];
+	a[j] = t;
+}
+
+/** procedure compare() 
+   The parameter dir indicates the sorting direction, ASCENDING 
+   or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+   then a[i] and a[j] are interchanged.
+**/
+inline void compare(int i, int j, int dir) {
+	if (dir==(a[i]>a[j])) 
+		exchange(i,j);
+}
+
+/** Procedure bitonicMerge() 
+   It recursively sorts a bitonic sequence in ascending order, 
+   if dir = ASCENDING, and in descending order otherwise. 
+   The sequence to be sorted starts at index position lo,
+   the parameter cbt is the number of elements to be sorted. 
+ **/
+void bitonicMerge(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		int k=cnt/2;
+		int i;
+		for (i=lo; i<lo+k; i++){
+			compare(i, i+k, dir);
+		}
+
+		bitonicMerge(lo, k, dir);
+		bitonicMerge(lo+k, k, dir);
+	}
+}
+
+/** function recBitonicSort() 
+    first produces a bitonic sequence by recursively sorting 
+    its two halves in opposite sorting orders, and then
+    calls bitonicMerge to make them in the same order 
+ **/
+void *recBitonicSort(void *threadArgs) {
+	recBitonicSortData *thisData = (recBitonicSortData *) threadArgs;
+	int lo = thisData->lo;
+	int cnt = thisData->cnt;
+	int dir = thisData->dir;
+
+	if (cnt>1) {
+		if (false){ //small sub-arrays best sorted using qsort
+			qsort(a+lo, cnt, sizeof(int), (dir == 1 ? qSortAscending : qSortDescending));
+		} else {
+			//plitts problem in two halfs and tries to create a new thread for each
+			//holds each half's index (from threads array)
+			int firstHalf = -1, myOtherHalf = -1;
+			//attribute for joinable threads
+			pthread_attr_t attr;
+			pthread_attr_init(&attr);
+			pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+
+			int k=cnt/2;
+			pthread_mutex_lock(&runningThreadsMutex); //locks running threads variable
+			if (runningThreads < threadsNum){
+				//arguments for first half
+				recBitonicSortData newThreadArgs;
+				newThreadArgs.lo = lo;
+				newThreadArgs.cnt = k;
+				newThreadArgs.dir = ASCENDING;
+				//tries to create a new thread with a pointer to it saved inside array "threads"
+				if (pthread_create(&threads[runningThreads], &attr, recBitonicSort, (void *) &newThreadArgs)){
+					printf("Error creating thread. Aborting.");
+					pthread_mutex_unlock(&runningThreadsMutex);
+					exit(1);
+				} else { //thread was successfully created
+					//keeps thread's index and updates running threads counter
+					firstHalf = runningThreads;
+					++runningThreads;
+					pthread_mutex_unlock(&runningThreadsMutex);
+				}
+			} else { //max threads number reached, does the job sequentially using qsort
+				pthread_mutex_unlock(&runningThreadsMutex);
+				qsort(a+lo, k, sizeof(int), qSortAscending);
+			}
+
+			pthread_mutex_lock(&runningThreadsMutex); //locks running threads variable
+			if (runningThreads < threadsNum){
+				//arguments for second half
+				recBitonicSortData newThreadArgs;
+				newThreadArgs.lo = lo+k;
+				newThreadArgs.cnt = k;
+				newThreadArgs.dir = DESCENDING;
+				//tries to create a new thread with a pointer to it saved inside array "threads"
+				if (pthread_create(&threads[runningThreads], &attr, recBitonicSort, (void *) &newThreadArgs)){
+					printf("Error creating thread. Aborting.");
+					pthread_mutex_unlock(&runningThreadsMutex);
+					exit(1);
+				} else { //thread was successfully created
+					//keeps thread's index and updates running threads counter
+					myOtherHalf = runningThreads;
+					++runningThreads;
+					pthread_mutex_unlock(&runningThreadsMutex);
+				}
+			} else { //max threads number reached, does the job sequentially using qsort
+				pthread_mutex_unlock(&runningThreadsMutex);
+				qsort(a+lo+k, k, sizeof(int), qSortDescending);
+			}
+
+			pthread_attr_destroy(&attr);
+
+			//achieves synchronization
+			if (firstHalf != -1){
+				pthread_join (threads[firstHalf], NULL);
+			}
+			if (myOtherHalf != -1){
+				pthread_join (threads[myOtherHalf], NULL);
+			}
+			bitonicMerge(lo, cnt, dir);
+		}
+	}
+}
+
+/** function sort() 
+   Caller of recBitonicSort for sorting the entire array of length N 
+   in ASCENDING order
+ **/
+void sort() {
+	recBitonicSortData newThreadArgs;
+	newThreadArgs.threadID = 1;
+	newThreadArgs.lo = 0;
+	newThreadArgs.cnt = N;
+	newThreadArgs.dir = ASCENDING;
+	recBitonicSort((void *) &newThreadArgs);
+}
+
+void *impBitonicSortThread(void * threadArgs){
+	//get variable values from struct
+	impBitonicSortThreadData *thisThreadData = (impBitonicSortThreadData *) threadArgs;
+	int i;
+	int N = thisThreadData->N;
+	int j = thisThreadData->j;
+	int k = thisThreadData->k;
+
+	for (i; i<N; i++) {
+		int ij=i^j;
+		if ((ij)>i) {
+			if ((i&k)==0 && a[i] > a[ij]) 
+				exchange(i,ij);
+			if ((i&k)!=0 && a[i] < a[ij])
+				exchange(i,ij);
+		}
+	}
+	pthread_exit(NULL);
+}
+
+/*
+  imperative version of bitonic sort
+*/
+void impBitonicSort() {
+	int t,j,k;
+
+	//attribute for joinable threads
+	pthread_attr_t attr;
+	pthread_attr_init(&attr);
+	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+	int threadN = N/threadsNum; //splitts work into 2^q sub-problems
+
+	for (k=2; k<=N; k+=k) {
+		for (j=k>>1; j>0; j=j>>1) {
+			//creates a new thread for each sub-problem
+			for (t = 0; t < threadsNum; ++t){
+				impBitonicSortThreadData newThreadArgs;
+				newThreadArgs.i = t * threadN;
+				newThreadArgs.N = (t + 1) * threadN;
+				newThreadArgs.j = j;
+				newThreadArgs.k = k;
+				int rc = pthread_create(&threads[t], &attr, impBitonicSortThread, (void *) &newThreadArgs);
+				if (rc){
+					printf("ERROR; return code from pthread_create() is %d\n", rc);
+					exit(-1);
+				}
+			}
+
+			//achieves synchronization
+			for(t = 0; t < threadsNum; ++t) {
+				pthread_join(threads[t], NULL);
+			}
+		}
+	}
+	pthread_attr_destroy(&attr);
+}
+
+/** function used by qsort for comparing as well as testing **/
+int qSortAscendingCompFuncWithTest (const void * a, const void * b) {
+	int result = ( *(int*)a - *(int*)b );
+	if (result > 0){
+		sortPass = false;
+	}
+	return result;
+}
+
+/** function used by qsort for comparing **/
+int qSortAscending (const void * a, const void * b) {
+	return ( *(int*)a - *(int*)b );
+}
+
+/** function used by qsort for comparing **/
+int qSortDescending (const void * a, const void * b) {
+	return ( *(int*)b - *(int*)a );
+}
\ No newline at end of file
diff --git a/openMP/bitonic.c b/openMP/bitonic.c
new file mode 100644
index 0000000..6aa7904
--- /dev/null
+++ b/openMP/bitonic.c
@@ -0,0 +1,304 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <sys/time.h>
+#include <omp.h>
+
+typedef enum { false, true } bool;
+struct timeval startwtime, endwtime;
+double seq_time;
+
+int threads; //number of threads
+int N;          // data array size
+int *a;         // data array to be sorted
+unsigned randSeed; //seed array initialisation
+bool sortPass; //flag showing whether the test passed or not
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+//min lenght of an array to be sorted by bitonicMerge in parallel manner
+const int REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN = (1 << 12) - 1;
+//min lenght of an array to be merged by bitonicMerge in parallel manner
+const int REC_BITONIC_MERGE_PARALLEL_CALL_MIN = (1 << 8) - 1;
+//min lenght of an array to be sorted in parallel manner
+const int REC_BITONIC_SORT_PARALLEL_MIN = (1 << 22) + 1;
+
+void getArgs(int argc, char** argv);
+void init(void);
+void print(void);
+void sort(void);
+void test(void);
+void qSortTest(void);
+void exchange(int i, int j);
+void compare(int i, int j, int dir);
+void bitonicMerge(int lo, int cnt, int dir);
+void recBitonicSort(int lo, int cnt, int dir);
+void impBitonicSort(void);
+int qSortAscendingCompFuncWithTest (const void * a, const void * b);
+int qSortAscending (const void * a, const void * b);
+int qSortDescending (const void * a, const void * b);
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+	getArgs(argc, argv);
+	a = (int *) malloc(N * sizeof(int));
+	randSeed = (unsigned) time(NULL);
+
+	omp_set_dynamic(0);
+	omp_set_num_threads(threads);
+
+	//Sorts using the qSort algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	qsort(a, N, sizeof(int), qSortAscending);
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("qSort wall clock time = %f\n\n", seq_time);
+
+	//Sorts using the imperative bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	impBitonicSort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("Imperative wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	//Sorts using the recursive bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	sort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("\nRecursive wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	free(a);
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+void getArgs(int argc, char** argv){
+	if (argc != 3) {
+		printf("Usage: %s p q\nwhere:\n\tP=2^p is the the number of threads(power of two)\n\tN=2^q is problem size (power of two)\n", 
+			argv[0]);
+		exit(1);
+	}
+	threads = 1<<atoi(argv[1]);
+	N = 1<<atoi(argv[2]);
+}
+
+/** procedure test() : verify sort results **/
+void test() {
+	int pass = 1;
+	int i;
+	for (i = 1; i < N; i++) {
+		pass &= (a[i-1] <= a[i]);
+	}
+	printf("\tTEST\t\t%s\n",(pass) ? "PASSed" : "FAILed");
+}
+
+/** procedure qSortTest() : verify sort results using qsort method **/
+void qSortTest(){
+	sortPass = true;
+	qsort(a, N, sizeof(int), qSortAscendingCompFuncWithTest);
+	printf("\tQSORT TEST\t%s\n",(sortPass) ? "PASSed" : "FAILed");
+}
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+	srand(randSeed);
+	int i;
+	for (i = 0; i < N; i++) {
+		a[i] = rand() % N; // (N - i);
+	}
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+	int i;
+	for (i = 0; i < N; i++) {
+		printf("%d\n", a[i]);
+	}
+	printf("\n");
+}
+
+/** INLINE procedure exchange() : pair swap **/
+inline void exchange(int i, int j) {
+	int t;
+	t = a[i];
+	a[i] = a[j];
+	a[j] = t;
+}
+
+/** procedure compare() 
+   The parameter dir indicates the sorting direction, ASCENDING 
+   or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+   then a[i] and a[j] are interchanged.
+**/
+inline void compare(int i, int j, int dir) {
+	if (dir==(a[i]>a[j])) 
+		exchange(i,j);
+}
+
+/** Procedure bitonicMerge() 
+   It recursively sorts a bitonic sequence in ascending order, 
+   if dir = ASCENDING, and in descending order otherwise. 
+   The sequence to be sorted starts at index position lo,
+   the parameter cbt is the number of elements to be sorted. 
+ **/
+void bitonicMerge(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		int k=cnt/2;
+		int i;
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN){
+			#pragma omp parallel for
+			for (i=lo; i<lo+k; i++)
+				compare(i, i+k, dir);
+		} else {
+			for (i=lo; i<lo+k; i++){
+				compare(i, i+k, dir);
+			}
+		}
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_CALL_MIN){
+			#pragma omp parallel sections
+			{
+				#pragma omp section
+				{
+					bitonicMerge(lo, k, dir);
+				}
+				#pragma omp section
+				{
+					bitonicMerge(lo+k, k, dir);
+				}
+			}
+		} else {
+			bitonicMerge(lo, k, dir);
+			bitonicMerge(lo+k, k, dir);
+		}
+	}
+}
+
+/** function recBitonicSort() 
+    first produces a bitonic sequence by recursively sorting 
+    its two halves in opposite sorting orders, and then
+    calls bitonicMerge to make them in the same order 
+ **/
+void recBitonicSort(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		if (cnt < REC_BITONIC_SORT_PARALLEL_MIN){
+			qsort(a+lo, cnt, sizeof(int), (dir == 1 ? qSortAscending : qSortDescending));
+			return;
+		}
+		int k=cnt/2;
+		#pragma omp task
+		{
+			recBitonicSort(lo, k, ASCENDING);
+		}
+		
+		#pragma omp task
+		{
+			recBitonicSort(lo+k, k, DESCENDING);
+		}
+		#pragma omp taskwait
+		bitonicMerge(lo, cnt, dir);
+	}
+}
+
+/** function sort() 
+   Caller of recBitonicSort for sorting the entire array of length N 
+   in ASCENDING order
+ **/
+void sort() {
+	#pragma omp parallel num_threads(threads)
+	#pragma omp single nowait
+	recBitonicSort(0, N, ASCENDING);
+}
+
+/*
+  imperative version of bitonic sort
+*/
+void impBitonicSort() {
+
+	int i,j,k;
+
+	for (k=2; k<=N; k=2*k) {
+		for (j=k>>1; j>0; j=j>>1) {
+			#pragma omp parallel for num_threads(threads)
+			for (i=0; i<N; i++) {
+				int ij=i^j;
+				if ((ij)>i) {
+					if ((i&k)==0 && a[i] > a[ij]) 
+						exchange(i,ij);
+					if ((i&k)!=0 && a[i] < a[ij])
+						exchange(i,ij);
+				}
+			}
+		}
+	}
+}
+
+/** function used by qsort for comparing as well as testing **/
+int qSortAscendingCompFuncWithTest (const void * a, const void * b) {
+	int result = ( *(int*)a - *(int*)b );
+	if (result > 0){
+		sortPass = false;
+	}
+	return result;
+}
+
+/** function used by qsort for comparing **/
+int qSortAscending (const void * a, const void * b) {
+	return ( *(int*)a - *(int*)b );
+}
+
+/** function used by qsort for comparing **/
+int qSortDescending (const void * a, const void * b) {
+	return ( *(int*)b - *(int*)a );
+}
\ No newline at end of file
diff --git a/pthreads/bitonic.c b/pthreads/bitonic.c
new file mode 100644
index 0000000..706a32e
--- /dev/null
+++ b/pthreads/bitonic.c
@@ -0,0 +1,395 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
+#include <pthread.h>
+
+typedef enum { false, true } bool;
+struct timeval startwtime, endwtime;
+double seq_time;
+
+int threadsNum; //number of threads
+int N; // data array size
+int *a; // data array to be sorted
+unsigned randSeed; //seed array initialisation
+bool sortPass; //flag showing whether the test passed or not
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+//min lenght of an array to be sorted in parallel manner
+const int REC_BITONIC_SORT_PARALLEL_MIN = (1 << 22) + 1;
+
+//structs for parallel functions
+typedef struct recBitonicSortData{
+	int threadID;
+	int lo;
+	int cnt;
+	int dir;
+} recBitonicSortData;
+
+typedef struct impBitonicSortThreadData{
+	int i;
+	int N;
+	int j;
+	int k;
+} impBitonicSortThreadData;
+
+pthread_t *threads; //array that holds pointers to all threads
+int runningThreads = 0; //number of threads currently running
+pthread_mutex_t runningThreadsMutex = PTHREAD_MUTEX_INITIALIZER;
+
+void getArgs(int argc, char** argv);
+void init(void);
+void print(void);
+void sort(void);
+void test(void);
+void qSortTest(void);
+void exchange(int i, int j);
+void compare(int i, int j, int dir);
+void bitonicMerge(int lo, int cnt, int dir);
+void *recBitonicSort(void *threadArgs);
+void *impBitonicSortThread(void * threadArgs);
+void impBitonicSort(void);
+int qSortAscendingCompFuncWithTest (const void * a, const void * b);
+int qSortAscending (const void * a, const void * b);
+int qSortDescending (const void * a, const void * b);
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+	getArgs(argc, argv);
+	a = (int *) malloc(N * sizeof(int));
+	randSeed = (unsigned) time(NULL);
+
+	//allocates space for an array that holds pointers to all threads
+	threads = (pthread_t *)malloc(sizeof(pthread_t)*threadsNum);
+
+	//Sorts using the qSort algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	qsort(a, N, sizeof(int), qSortAscending);
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("qSort wall clock time = %f\n\n", seq_time);
+
+	//Sorts using the imperative bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	impBitonicSort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("Imperative wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	//Sorts using the recursive bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	sort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("\nRecursive wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	free(threads);
+	free(a);
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+void getArgs(int argc, char** argv){
+	if (argc != 3) {
+		printf("Usage: %s p q\nwhere:\n\tP=2^p is the the number of threads(power of two)\n\tN=2^q is problem size (power of two)\n", 
+			argv[0]);
+		exit(1);
+	}
+	threadsNum = 1<<atoi(argv[1]);
+	N = 1<<atoi(argv[2]);
+}
+
+/** procedure test() : verify sort results **/
+void test() {
+	int pass = 1;
+	int i;
+	for (i = 1; i < N; i++) {
+		pass &= (a[i-1] <= a[i]);
+	}
+	printf("\tTEST\t\t%s\n",(pass) ? "PASSed" : "FAILed");
+}
+
+/** procedure qSortTest() : verify sort results using qsort method **/
+void qSortTest(){
+	sortPass = true;
+	qsort(a, N, sizeof(int), qSortAscendingCompFuncWithTest);
+	printf("\tQSORT TEST\t%s\n",(sortPass) ? "PASSed" : "FAILed");
+}
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+	srand(randSeed);
+	int i;
+	for (i = 0; i < N; i++) {
+		a[i] = rand() % N; // (N - i);
+	}
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+	int i;
+	for (i = 0; i < N; i++) {
+		printf("%d\n", a[i]);
+	}
+	printf("\n");
+}
+
+/** INLINE procedure exchange() : pair swap **/
+inline void exchange(int i, int j) {
+	int t;
+	t = a[i];
+	a[i] = a[j];
+	a[j] = t;
+}
+
+/** procedure compare() 
+   The parameter dir indicates the sorting direction, ASCENDING 
+   or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+   then a[i] and a[j] are interchanged.
+**/
+inline void compare(int i, int j, int dir) {
+	if (dir==(a[i]>a[j])) 
+		exchange(i,j);
+}
+
+/** Procedure bitonicMerge() 
+   It recursively sorts a bitonic sequence in ascending order, 
+   if dir = ASCENDING, and in descending order otherwise. 
+   The sequence to be sorted starts at index position lo,
+   the parameter cbt is the number of elements to be sorted. 
+ **/
+void bitonicMerge(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		int k=cnt/2;
+		int i;
+		for (i=lo; i<lo+k; i++){
+			compare(i, i+k, dir);
+		}
+
+		bitonicMerge(lo, k, dir);
+		bitonicMerge(lo+k, k, dir);
+	}
+}
+
+/** function recBitonicSort() 
+    first produces a bitonic sequence by recursively sorting 
+    its two halves in opposite sorting orders, and then
+    calls bitonicMerge to make them in the same order 
+ **/
+void *recBitonicSort(void *threadArgs) {
+	recBitonicSortData *thisData = (recBitonicSortData *) threadArgs;
+	int lo = thisData->lo;
+	int cnt = thisData->cnt;
+	int dir = thisData->dir;
+
+	if (cnt>1) {
+		if (cnt < REC_BITONIC_SORT_PARALLEL_MIN){ //small sub-arrays best sorted using qsort
+			qsort(a+lo, cnt, sizeof(int), (dir == 1 ? qSortAscending : qSortDescending));
+		} else {
+			//plitts problem in two halfs and tries to create a new thread for each
+			//holds each half's index (from threads array)
+			int firstHalf = -1, myOtherHalf = -1;
+			//attribute for joinable threads
+			pthread_attr_t attr;
+			pthread_attr_init(&attr);
+			pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+
+			int k=cnt/2;
+			pthread_mutex_lock(&runningThreadsMutex); //locks running threads variable
+			if (runningThreads < threadsNum){
+				//arguments for first half
+				recBitonicSortData newThreadArgs;
+				newThreadArgs.lo = lo;
+				newThreadArgs.cnt = k;
+				newThreadArgs.dir = ASCENDING;
+				//tries to create a new thread with a pointer to it saved inside array "threads"
+				if (pthread_create(&threads[runningThreads], &attr, recBitonicSort, (void *) &newThreadArgs)){
+					printf("Error creating thread. Aborting.");
+					pthread_mutex_unlock(&runningThreadsMutex);
+					exit(1);
+				} else { //thread was successfully created
+					//keeps thread's index and updates running threads counter
+					firstHalf = runningThreads;
+					++runningThreads;
+					pthread_mutex_unlock(&runningThreadsMutex);
+				}
+			} else { //max threads number reached, does the job sequentially using qsort
+				pthread_mutex_unlock(&runningThreadsMutex);
+				qsort(a+lo, k, sizeof(int), qSortAscending);
+			}
+
+			pthread_mutex_lock(&runningThreadsMutex); //locks running threads variable
+			if (runningThreads < threadsNum){
+				//arguments for second half
+				recBitonicSortData newThreadArgs;
+				newThreadArgs.lo = lo+k;
+				newThreadArgs.cnt = k;
+				newThreadArgs.dir = DESCENDING;
+				//tries to create a new thread with a pointer to it saved inside array "threads"
+				if (pthread_create(&threads[runningThreads], &attr, recBitonicSort, (void *) &newThreadArgs)){
+					printf("Error creating thread. Aborting.");
+					pthread_mutex_unlock(&runningThreadsMutex);
+					exit(1);
+				} else { //thread was successfully created
+					//keeps thread's index and updates running threads counter
+					myOtherHalf = runningThreads;
+					++runningThreads;
+					pthread_mutex_unlock(&runningThreadsMutex);
+				}
+			} else { //max threads number reached, does the job sequentially using qsort
+				pthread_mutex_unlock(&runningThreadsMutex);
+				qsort(a+lo+k, k, sizeof(int), qSortDescending);
+			}
+
+			pthread_attr_destroy(&attr);
+
+			//achieves synchronization
+			if (firstHalf != -1){
+				pthread_join (threads[firstHalf], NULL);
+			}
+			if (myOtherHalf != -1){
+				pthread_join (threads[myOtherHalf], NULL);
+			}
+			bitonicMerge(lo, cnt, dir);
+		}
+	}
+}
+
+/** function sort() 
+   Caller of recBitonicSort for sorting the entire array of length N 
+   in ASCENDING order
+ **/
+void sort() {
+	recBitonicSortData newThreadArgs;
+	newThreadArgs.threadID = 1;
+	newThreadArgs.lo = 0;
+	newThreadArgs.cnt = N;
+	newThreadArgs.dir = ASCENDING;
+	recBitonicSort((void *) &newThreadArgs);
+}
+
+void *impBitonicSortThread(void * threadArgs){
+	//get variable values from struct
+	impBitonicSortThreadData *thisThreadData = (impBitonicSortThreadData *) threadArgs;
+	int i;
+	int N = thisThreadData->N;
+	int j = thisThreadData->j;
+	int k = thisThreadData->k;
+
+	for (i; i<N; i++) {
+		int ij=i^j;
+		if ((ij)>i) {
+			if ((i&k)==0 && a[i] > a[ij]) 
+				exchange(i,ij);
+			if ((i&k)!=0 && a[i] < a[ij])
+				exchange(i,ij);
+		}
+	}
+	pthread_exit(NULL);
+}
+
+/*
+  imperative version of bitonic sort
+*/
+void impBitonicSort() {
+	int t,j,k;
+
+	//attribute for joinable threads
+	pthread_attr_t attr;
+	pthread_attr_init(&attr);
+	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+	int threadN = N/threadsNum; //splitts work into 2^q sub-problems
+
+	for (k=2; k<=N; k+=k) {
+		for (j=k>>1; j>0; j=j>>1) {
+			//creates a new thread for each sub-problem
+			for (t = 0; t < threadsNum; ++t){
+				impBitonicSortThreadData newThreadArgs;
+				newThreadArgs.i = t * threadN;
+				newThreadArgs.N = (t + 1) * threadN;
+				newThreadArgs.j = j;
+				newThreadArgs.k = k;
+				int rc = pthread_create(&threads[t], &attr, impBitonicSortThread, (void *) &newThreadArgs);
+				if (rc){
+					printf("ERROR; return code from pthread_create() is %d\n", rc);
+					exit(-1);
+				}
+			}
+
+			//achieves synchronization
+			for(t = 0; t < threadsNum; ++t) {
+				pthread_join(threads[t], NULL);
+			}
+		}
+	}
+	pthread_attr_destroy(&attr);
+}
+
+/** function used by qsort for comparing as well as testing **/
+int qSortAscendingCompFuncWithTest (const void * a, const void * b) {
+	int result = ( *(int*)a - *(int*)b );
+	if (result > 0){
+		sortPass = false;
+	}
+	return result;
+}
+
+/** function used by qsort for comparing **/
+int qSortAscending (const void * a, const void * b) {
+	return ( *(int*)a - *(int*)b );
+}
+
+/** function used by qsort for comparing **/
+int qSortDescending (const void * a, const void * b) {
+	return ( *(int*)b - *(int*)a );
+}
\ No newline at end of file
diff --git a/pthreads/bitonicImp.c b/pthreads/bitonicImp.c
new file mode 100644
index 0000000..6c678b9
--- /dev/null
+++ b/pthreads/bitonicImp.c
@@ -0,0 +1,249 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
+#include <pthread.h>
+
+typedef enum { false, true } bool;
+struct timeval startwtime, endwtime;
+double seq_time;
+
+int threadsNum; //number of threads
+int N; // data array size
+int *a; // data array to be sorted
+unsigned randSeed; //seed array initialisation
+bool sortPass; //flag showing whether the test passed or not
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+const int REC_BITONIC_MERGE_PARALLEL_GRAINSIZE = 1 << 14;
+const int REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN = (1 << 12) - 1;
+const int REC_BITONIC_MERGE_PARALLEL_CALL_MIN = (1 << 8) - 1;
+const int REC_BITONIC_SORT_PARALLEL_MIN = (1 << 22) + 1;
+
+typedef struct impBitonicSortThreadData{
+	int i;
+	int N;
+	int j;
+	int k;
+} impBitonicSortThreadData;
+
+void getArgs(int argc, char** argv);
+void init(void);
+void print(void);
+void sort(void);
+void test(void);
+void qSortTest(void);
+void exchange(int i, int j);
+void compare(int i, int j, int dir);
+void *impBitonicSortThread(void * threadArgs);
+void impBitonicSort(void);
+int qSortAscendingCompFuncWithTest (const void * a, const void * b);
+int qSortAscending (const void * a, const void * b);
+int qSortDescending (const void * a, const void * b);
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+	getArgs(argc, argv);
+	a = (int *) malloc(N * sizeof(int));
+	randSeed = (unsigned) time(NULL);
+
+	//Sorts using the qSort algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	qsort(a, N, sizeof(int), qSortAscending);
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("qSort wall clock time = %f\n\n", seq_time);
+
+	//Sorts using the imperative bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	impBitonicSort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("Imperative wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	free(a);
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+void getArgs(int argc, char** argv){
+	if (argc != 3) {
+		printf("Usage: %s p q\nwhere:\n\tP=2^p is the the number of threads(power of two)\n\tN=2^q is problem size (power of two)\n", 
+			argv[0]);
+		exit(1);
+	}
+	threadsNum = 1<<atoi(argv[1]);
+	N = 1<<atoi(argv[2]);
+}
+
+/** procedure test() : verify sort results **/
+void test() {
+	int pass = 1;
+	int i;
+	for (i = 1; i < N; i++) {
+		pass &= (a[i-1] <= a[i]);
+	}
+	printf("\tTEST\t\t%s\n",(pass) ? "PASSed" : "FAILed");
+}
+
+/** procedure qSortTest() : verify sort results using qsort method **/
+void qSortTest(){
+	sortPass = true;
+	qsort(a, N, sizeof(int), qSortAscendingCompFuncWithTest);
+	printf("\tQSORT TEST\t%s\n",(sortPass) ? "PASSed" : "FAILed");
+}
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+	srand(randSeed);
+	int i;
+	for (i = 0; i < N; i++) {
+		a[i] = rand() % N; // (N - i);
+	}
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+	int i;
+	for (i = 0; i < N; i++) {
+		printf("%d\n", a[i]);
+	}
+	printf("\n");
+}
+
+/** INLINE procedure exchange() : pair swap **/
+inline void exchange(int i, int j) {
+	int t;
+	t = a[i];
+	a[i] = a[j];
+	a[j] = t;
+}
+
+/** procedure compare() 
+   The parameter dir indicates the sorting direction, ASCENDING 
+   or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+   then a[i] and a[j] are interchanged.
+**/
+inline void compare(int i, int j, int dir) {
+	if (dir==(a[i]>a[j])) 
+		exchange(i,j);
+}
+
+void *impBitonicSortThread(void * threadArgs){
+	impBitonicSortThreadData *thisThreadData = (impBitonicSortThreadData *) threadArgs;
+	int i;
+	int N = thisThreadData->N;
+	int j = thisThreadData->j;
+	int k = thisThreadData->k;
+
+	for (i; i<N; i++) {
+		int ij=i^j;
+		if ((ij)>i) {
+			if ((i&k)==0 && a[i] > a[ij]) 
+				exchange(i,ij);
+			if ((i&k)!=0 && a[i] < a[ij])
+				exchange(i,ij);
+		}
+	}
+	pthread_exit(NULL);
+}
+
+/*
+  imperative version of bitonic sort
+*/
+void impBitonicSort() {
+	int t,j,k;
+
+	impBitonicSortThreadData impBitonicSortThreadDataArray[threadsNum];
+	pthread_t threads[threadsNum];
+	pthread_attr_t attr;
+	pthread_attr_init(&attr);
+	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+	int threadN = N/threadsNum;
+
+	for (k=2; k<=N; k+=k) {
+		for (j=k>>1; j>0; j=j>>1) {
+			for (t = 0; t < threadsNum; ++t){
+				impBitonicSortThreadDataArray[t].i = t * threadN;
+				impBitonicSortThreadDataArray[t].N = (t + 1) * threadN;
+				impBitonicSortThreadDataArray[t].j = j;
+				impBitonicSortThreadDataArray[t].k = k;
+				int rc = pthread_create(&threads[t], &attr, impBitonicSortThread, (void *) &impBitonicSortThreadDataArray[t]);
+				if (rc){
+					printf("ERROR; return code from pthread_create() is %d\n", rc);
+					exit(-1);
+				}
+			}
+			void *status;
+			for(t = 0; t < threadsNum; ++t) {
+				int rc = pthread_join(threads[t], &status);
+				if (rc) {
+					printf("ERROR; return code from pthread_join() is %d\n", rc);
+					exit(-1);
+				}
+			}
+		}
+	}
+	pthread_attr_destroy(&attr);
+}
+
+/** function used by qsort for comparing as well as testing **/
+int qSortAscendingCompFuncWithTest (const void * a, const void * b) {
+	int result = ( *(int*)a - *(int*)b );
+	if (result > 0){
+		sortPass = false;
+	}
+	return result;
+}
+
+/** function used by qsort for comparing **/
+int qSortAscending (const void * a, const void * b) {
+	return ( *(int*)a - *(int*)b );
+}
+
+/** function used by qsort for comparing **/
+int qSortDescending (const void * a, const void * b) {
+	return ( *(int*)b - *(int*)a );
+}
\ No newline at end of file
diff --git a/pthreads/bitonicRec.c b/pthreads/bitonicRec.c
new file mode 100644
index 0000000..5353dc8
--- /dev/null
+++ b/pthreads/bitonicRec.c
@@ -0,0 +1,320 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
+#include <pthread.h>
+
+typedef enum { false, true } bool;
+struct timeval startwtime, endwtime;
+double seq_time;
+
+int threadsNum; //number of threads
+int N; // data array size
+int *a; // data array to be sorted
+unsigned randSeed; //seed array initialisation
+bool sortPass; //flag showing whether the test passed or not
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+const int REC_BITONIC_MERGE_PARALLEL_GRAINSIZE = 1 << 14;
+const int REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN = (1 << 12) - 1;
+const int REC_BITONIC_MERGE_PARALLEL_CALL_MIN = (1 << 8) - 1;
+const int REC_BITONIC_SORT_PARALLEL_MIN = (1 << 22) + 1;
+
+typedef struct recBitonicSortData{
+	int threadID;
+	int lo;
+	int cnt;
+	int dir;
+} recBitonicSortData;
+
+pthread_t *threads;
+int runningThreads = 1;
+pthread_mutex_t runningThreadsMutex = PTHREAD_MUTEX_INITIALIZER;
+
+void getArgs(int argc, char** argv);
+void init(void);
+void print(void);
+void sort(void);
+void test(void);
+void qSortTest(void);
+void exchange(int i, int j);
+void compare(int i, int j, int dir);
+void bitonicMerge(int lo, int cnt, int dir);
+void *recBitonicSort(void *threadArgs);
+int qSortAscendingCompFuncWithTest (const void * a, const void * b);
+int qSortAscending (const void * a, const void * b);
+int qSortDescending (const void * a, const void * b);
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+	getArgs(argc, argv);
+	a = (int *) malloc(N * sizeof(int));
+	randSeed = (unsigned) time(NULL);
+
+	threads = (pthread_t *)malloc(sizeof(pthread_t)*threadsNum);
+
+	//Sorts using the qSort algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	qsort(a, N, sizeof(int), qSortAscending);
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("qSort wall clock time = %f\n\n", seq_time);
+
+	//Sorts using the recursive bitonic algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	sort();
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("\nRecursive wall clock time = %f\n", seq_time);
+
+	test();
+	qSortTest();
+
+	free(a);
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+void getArgs(int argc, char** argv){
+	if (argc != 3) {
+		printf("Usage: %s p q\nwhere:\n\tP=2^p is the the number of threads(power of two)\n\tN=2^q is problem size (power of two)\n", 
+			argv[0]);
+		exit(1);
+	}
+	threadsNum = 1<<atoi(argv[1]);
+	N = 1<<atoi(argv[2]);
+}
+
+/** procedure test() : verify sort results **/
+void test() {
+	int pass = 1;
+	int i;
+	for (i = 1; i < N; i++) {
+		pass &= (a[i-1] <= a[i]);
+	}
+	printf("\tTEST\t\t%s\n",(pass) ? "PASSed" : "FAILed");
+}
+
+/** procedure qSortTest() : verify sort results using qsort method **/
+void qSortTest(){
+	sortPass = true;
+	qsort(a, N, sizeof(int), qSortAscendingCompFuncWithTest);
+	printf("\tQSORT TEST\t%s\n",(sortPass) ? "PASSed" : "FAILed");
+}
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+	srand(randSeed);
+	int i;
+	for (i = 0; i < N; i++) {
+		a[i] = rand() % N; // (N - i);
+	}
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+	int i;
+	for (i = 0; i < N; i++) {
+		printf("%d\n", a[i]);
+	}
+	printf("\n");
+}
+
+/** INLINE procedure exchange() : pair swap **/
+inline void exchange(int i, int j) {
+	int t;
+	t = a[i];
+	a[i] = a[j];
+	a[j] = t;
+}
+
+/** procedure compare() 
+   The parameter dir indicates the sorting direction, ASCENDING 
+   or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+   then a[i] and a[j] are interchanged.
+**/
+inline void compare(int i, int j, int dir) {
+	if (dir==(a[i]>a[j])) 
+		exchange(i,j);
+}
+
+/** Procedure bitonicMerge() 
+   It recursively sorts a bitonic sequence in ascending order, 
+   if dir = ASCENDING, and in descending order otherwise. 
+   The sequence to be sorted starts at index position lo,
+   the parameter cbt is the number of elements to be sorted. 
+ **/
+void bitonicMerge(int lo, int cnt, int dir) {
+	if (cnt>1) {
+		int k=cnt/2;
+		int i;
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_COMPARE_MIN){
+			for (i=lo; i<lo+k; i++){
+				compare(i, i+k, dir);
+			}
+		} else {
+			for (i=lo; i<lo+k; i++){
+				compare(i, i+k, dir);
+			}
+		}
+
+		if (cnt > REC_BITONIC_MERGE_PARALLEL_CALL_MIN){
+			bitonicMerge(lo, k, dir);
+			bitonicMerge(lo+k, k, dir);
+		} else{
+			bitonicMerge(lo, k, dir);
+			bitonicMerge(lo+k, k, dir);
+		}
+	}
+}
+
+/** function recBitonicSort() 
+    first produces a bitonic sequence by recursively sorting 
+    its two halves in opposite sorting orders, and then
+    calls bitonicMerge to make them in the same order 
+ **/
+void *recBitonicSort(void *threadArgs) {
+	recBitonicSortData *thisData = (recBitonicSortData *) threadArgs;
+	int threadID = thisData->threadID;
+	int lo = thisData->lo;
+	int cnt = thisData->cnt;
+	int dir = thisData->dir;
+
+	if (cnt>1) {
+		if (cnt < REC_BITONIC_SORT_PARALLEL_MIN){
+			qsort(a+lo, cnt, sizeof(int), (dir == 1 ? qSortAscending : qSortDescending));
+		} else {
+			pthread_t firstHalf, myOtherHalf;
+			pthread_attr_t attr;
+			pthread_attr_init(&attr);
+			pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
+
+			int k=cnt/2;
+			pthread_mutex_lock(&runningThreadsMutex);
+			if (runningThreads < threadsNum){
+				recBitonicSortData newThreadArgs;
+				newThreadArgs.threadID = runningThreads + 1;
+				newThreadArgs.lo = lo;
+				newThreadArgs.cnt = k;
+				newThreadArgs.dir = ASCENDING;
+				if (pthread_create(&firstHalf, &attr, recBitonicSort, (void *) &newThreadArgs)){
+					printf("Error creating thread. Aborting.");
+					pthread_mutex_unlock(&runningThreadsMutex);
+					exit(1);
+				} else {
+					++runningThreads;
+					pthread_mutex_unlock(&runningThreadsMutex);
+				}
+			} else {
+				pthread_mutex_unlock(&runningThreadsMutex);
+				qsort(a+lo, k, sizeof(int), qSortAscending);
+			}
+
+			pthread_mutex_lock(&runningThreadsMutex);
+			if (runningThreads < threadsNum){
+				recBitonicSortData newThreadArgs;
+				newThreadArgs.threadID = runningThreads + 1;
+				newThreadArgs.lo = lo+k;
+				newThreadArgs.cnt = k;
+				newThreadArgs.dir = DESCENDING;
+				if (pthread_create(&myOtherHalf, &attr, recBitonicSort, (void *) &newThreadArgs)){
+					printf("Error creating thread. Aborting.");
+					pthread_mutex_unlock(&runningThreadsMutex);
+					exit(1);
+				} else {
+					++runningThreads;
+					pthread_mutex_unlock(&runningThreadsMutex);
+				}
+			} else {
+				pthread_mutex_unlock(&runningThreadsMutex);
+				qsort(a+lo+k, k, sizeof(int), qSortDescending);
+			}
+
+			pthread_attr_destroy(&attr);
+
+			if (&firstHalf != NULL){
+				pthread_join (firstHalf, NULL);
+			}
+			if (&firstHalf != NULL){
+				pthread_join (myOtherHalf, NULL);
+			}
+			bitonicMerge(lo, cnt, dir);
+		}
+	}
+
+	if (threadID > 1 && threadID < threadsNum){
+		pthread_exit(NULL);
+	}
+}
+
+/** function sort() 
+   Caller of recBitonicSort for sorting the entire array of length N 
+   in ASCENDING order
+ **/
+void sort() {
+	recBitonicSortData newThreadArgs;
+	newThreadArgs.threadID = 1;
+	newThreadArgs.lo = 0;
+	newThreadArgs.cnt = N;
+	newThreadArgs.dir = ASCENDING;
+	recBitonicSort((void *) &newThreadArgs);
+}
+
+/** function used by qsort for comparing as well as testing **/
+int qSortAscendingCompFuncWithTest (const void * a, const void * b) {
+	int result = ( *(int*)a - *(int*)b );
+	if (result > 0){
+		sortPass = false;
+	}
+	return result;
+}
+
+/** function used by qsort for comparing **/
+int qSortAscending (const void * a, const void * b) {
+	return ( *(int*)a - *(int*)b );
+}
+
+/** function used by qsort for comparing **/
+int qSortDescending (const void * a, const void * b) {
+	return ( *(int*)b - *(int*)a );
+}
\ No newline at end of file
diff --git a/qsort/qsort.c b/qsort/qsort.c
new file mode 100644
index 0000000..6bb0e0d
--- /dev/null
+++ b/qsort/qsort.c
@@ -0,0 +1,110 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
+
+typedef enum { false, true } bool;
+struct timeval startwtime, endwtime;
+double seq_time;
+
+int threads; //number of threads
+int N; // data array size
+int *a; // data array to be sorted
+unsigned randSeed; //seed array initialisation
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+
+void getArgs(int argc, char** argv);
+void init(void);
+void print(void);
+int qSortAscending (const void * a, const void * b);
+int qSortDescending (const void * a, const void * b);
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+	getArgs(argc, argv);
+	a = (int *) malloc(N * sizeof(int));
+	randSeed = (unsigned) time(NULL);
+
+	//Sorts using the qSort algorithm
+	init();
+
+	gettimeofday (&startwtime, NULL);
+	qsort(a, N, sizeof(int), qSortAscending);
+	gettimeofday (&endwtime, NULL);
+
+	seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		+ endwtime.tv_sec - startwtime.tv_sec);
+
+	printf("%f\n", seq_time);
+
+	free(a);
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+void getArgs(int argc, char** argv){
+	if (argc != 2) {
+		printf("Usage: %s p q\nwhere:\n\tP=2^p is the the number of threads(power of two)\n\tN=2^q is problem size (power of two)\n", 
+			argv[0]);
+		exit(1);
+	}
+	N = 1<<atoi(argv[1]);
+}
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+	srand(randSeed);
+	int i;
+	for (i = 0; i < N; i++) {
+		a[i] = rand() % N; // (N - i);
+	}
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+	int i;
+	for (i = 0; i < N; i++) {
+		printf("%d\n", a[i]);
+	}
+	printf("\n");
+}
+
+/** function used by qsort for comparing **/
+int qSortAscending (const void * a, const void * b) {
+	return ( *(int*)a - *(int*)b );
+}
+
+/** function used by qsort for comparing **/
+int qSortDescending (const void * a, const void * b) {
+	return ( *(int*)b - *(int*)a );
+}
\ No newline at end of file
diff --git a/seq/bitonic.c b/seq/bitonic.c
new file mode 100644
index 0000000..dfc3391
--- /dev/null
+++ b/seq/bitonic.c
@@ -0,0 +1,215 @@
+/*
+ bitonic.c 
+
+ This file contains two different implementations of the bitonic sort
+        recursive  version :  recBitonicSort()
+        imperative version :  impBitonicSort() 
+ 
+
+ The bitonic sort is also known as Batcher Sort. 
+ For a reference of the algorithm, see the article titled 
+ Sorting networks and their applications by K. E. Batcher in 1968 
+
+
+ The following codes take references to the codes avaiable at 
+
+ http://www.cag.lcs.mit.edu/streamit/results/bitonic/code/c/bitonic.c
+
+ http://www.tools-of-computing.com/tc/CS/Sorts/bitonic_sort.htm
+
+ http://www.iti.fh-flensburg.de/lang/algorithmen/sortieren/bitonic/bitonicen.htm 
+ */
+
+/* 
+------- ---------------------- 
+   Nikos Pitsianis, Duke CS 
+-----------------------------
+*/
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+
+struct timeval startwtime, endwtime;
+double seq_time;
+
+
+int N;          // data array size
+int *a;         // data array to be sorted
+
+const int ASCENDING  = 1;
+const int DESCENDING = 0;
+
+
+void init(void);
+void print(void);
+void sort(void);
+void test(void);
+inline void exchange(int i, int j);
+void compare(int i, int j, int dir);
+void bitonicMerge(int lo, int cnt, int dir);
+void recBitonicSort(int lo, int cnt, int dir);
+void impBitonicSort(void);
+
+
+/** the main program **/ 
+int main(int argc, char **argv) {
+
+  if (argc != 2) {
+    printf("Usage: %s q\n  where n=2^q is problem size (power of two)\n", 
+	   argv[0]);
+    exit(1);
+  }
+
+  N = 1<<atoi(argv[1]);
+  a = (int *) malloc(N * sizeof(int));
+  
+  init();
+
+  gettimeofday (&startwtime, NULL);
+  impBitonicSort();
+  gettimeofday (&endwtime, NULL);
+
+  seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		      + endwtime.tv_sec - startwtime.tv_sec);
+
+  printf("Imperative wall clock time = %f\n", seq_time);
+
+  test();
+
+  init();
+  gettimeofday (&startwtime, NULL);
+  sort();
+  gettimeofday (&endwtime, NULL);
+
+  seq_time = (double)((endwtime.tv_usec - startwtime.tv_usec)/1.0e6
+		      + endwtime.tv_sec - startwtime.tv_sec);
+
+  printf("Recursive wall clock time = %f\n", seq_time);
+
+  test();
+
+  // print();
+}
+
+/** -------------- SUB-PROCEDURES  ----------------- **/ 
+
+/** procedure test() : verify sort results **/
+void test() {
+  int pass = 1;
+  int i;
+  for (i = 1; i < N; i++) {
+    pass &= (a[i-1] <= a[i]);
+  }
+
+  printf(" TEST %s\n",(pass) ? "PASSed" : "FAILed");
+}
+
+
+/** procedure init() : initialize array "a" with data **/
+void init() {
+  int i;
+  for (i = 0; i < N; i++) {
+    a[i] = rand() % N; // (N - i);
+  }
+}
+
+/** procedure  print() : print array elements **/
+void print() {
+  int i;
+  for (i = 0; i < N; i++) {
+    printf("%d\n", a[i]);
+  }
+  printf("\n");
+}
+
+
+/** INLINE procedure exchange() : pair swap **/
+inline void exchange(int i, int j) {
+  int t;
+  t = a[i];
+  a[i] = a[j];
+  a[j] = t;
+}
+
+
+
+/** procedure compare() 
+   The parameter dir indicates the sorting direction, ASCENDING 
+   or DESCENDING; if (a[i] > a[j]) agrees with the direction, 
+   then a[i] and a[j] are interchanged.
+**/
+inline void compare(int i, int j, int dir) {
+  if (dir==(a[i]>a[j])) 
+    exchange(i,j);
+}
+
+
+
+
+/** Procedure bitonicMerge() 
+   It recursively sorts a bitonic sequence in ascending order, 
+   if dir = ASCENDING, and in descending order otherwise. 
+   The sequence to be sorted starts at index position lo,
+   the parameter cbt is the number of elements to be sorted. 
+ **/
+void bitonicMerge(int lo, int cnt, int dir) {
+  if (cnt>1) {
+    int k=cnt/2;
+    int i;
+    for (i=lo; i<lo+k; i++)
+      compare(i, i+k, dir);
+    bitonicMerge(lo, k, dir);
+    bitonicMerge(lo+k, k, dir);
+  }
+}
+
+
+
+/** function recBitonicSort() 
+    first produces a bitonic sequence by recursively sorting 
+    its two halves in opposite sorting orders, and then
+    calls bitonicMerge to make them in the same order 
+ **/
+void recBitonicSort(int lo, int cnt, int dir) {
+  if (cnt>1) {
+    int k=cnt/2;
+    recBitonicSort(lo, k, ASCENDING);
+    recBitonicSort(lo+k, k, DESCENDING);
+    bitonicMerge(lo, cnt, dir);
+  }
+}
+
+
+/** function sort() 
+   Caller of recBitonicSort for sorting the entire array of length N 
+   in ASCENDING order
+ **/
+void sort() {
+  recBitonicSort(0, N, ASCENDING);
+}
+
+
+
+/*
+  imperative version of bitonic sort
+*/
+void impBitonicSort() {
+
+  int i,j,k;
+  
+  for (k=2; k<=N; k=2*k) {
+    for (j=k>>1; j>0; j=j>>1) {
+      for (i=0; i<N; i++) {
+	int ij=i^j;
+	if ((ij)>i) {
+	  if ((i&k)==0 && a[i] > a[ij]) 
+	      exchange(i,ij);
+	  if ((i&k)!=0 && a[i] < a[ij])
+	      exchange(i,ij);
+	}
+      }
+    }
+  }
+}