better transposition algorithm

time.c

@@ -0,0 +1,62 @@
+#include <time.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <string.h>
+#include "lina.h"
+
+/* This function compares the lina_transpose
+** implementation against the naive implementation.
+*/
+
+#define check assert
+
+static void naive_transpose(double *A, double *B, int m, int n)
+{
+    assert(m > 0 && n > 0);
+    assert(A != NULL && B != NULL);
+
+    double *support = malloc(sizeof(*support) * m * n);
+
+    check(support != NULL);
+
+    memcpy(support, A, sizeof(*support) * m * n);
+
+    for(int i = 0; i < n; i++)
+        
+        for(int j = 0; j < m; j++)
+
+            B[j*n + i] = support[i*m + j];
+
+    free(support);
+}
+
+int main()
+{
+	int m = 1000;
+	int n = 100000;
+
+	double *big = malloc(sizeof(double) * m * n);
+	check(big != NULL);
+
+	memset(big, 0, sizeof(double) * m * n);
+
+	double t1, t2;
+	clock_t begin, end;
+
+	begin = clock();
+	lina_transpose(big, big, m, n);
+	end = clock();
+	t1 = (double) (end - begin) / CLOCKS_PER_SEC;
+
+	begin = clock();
+	naive_transpose(big, big, m, n);
+	end = clock();
+	t2 = (double) (end - begin) / CLOCKS_PER_SEC;
+
+	printf("lina_transpose took %gms\n", t1*1000);
+	printf("naive_transpose took %gms\n", t2*1000);
+
+	free(big);
+	return 0;
+}