ex4_array.c File Reference

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

Go to the source code of this file.

Macros
#define	SIZE   100000000
#define	GET_SEC(a, b)   ((b - a) / (double)CLOCKS_PER_SEC)

Functions
int	main (int argc, char **argv)

Macro Definition Documentation

#define GET_SEC	(		a,
			b
	)		((b - a) / (double)CLOCKS_PER_SEC)

Definition at line 7 of file ex4_array.c.

#define SIZE   100000000

Definition at line 5 of file ex4_array.c.

Function Documentation

int main	(	int	argc,
		char **	argv
	)

Definition at line 9 of file ex4_array.c.

{
   clock_t start;
   double* x = malloc(SIZE * sizeof(*x));
   double  sum;
   
   for(int i = 0; i < SIZE; i++)
      x[i] = i + 1.0;
   
   sum = 0.0; start = clock();

   /* In order 1 */
   for(int i = 0; i < SIZE; i++)
      sum += x[i];

   printf("IO time=%.3f sum=%.1f\n", GET_SEC(start, clock()), sum);

   sum = 0.0; start = clock();

   /* In order 2 */
   for(int k = 0; k < 100; k++)
      for(int i = 0; i < SIZE / 100; i++)
         sum += x[k * (SIZE / 100) + i];

   printf("O1 time=%.3f sum=%.1f\n", GET_SEC(start, clock()), sum);

   sum = 0.0; start = clock();
   
   for(int i = 0; i < SIZE / 100; i++)
      for(int k = 0; k < 100; k++)
         sum += x[k * (SIZE / 100) + i];

   printf("OH time=%.3f sum=%.1f\n", GET_SEC(start, clock()), sum);

   sum = 0.0; start = clock();
   
   for(int i = 0; i < SIZE / 1000; i++)
      for(int k = 0; k < 1000; k++)
         sum += x[k * (SIZE / 1000) + i];

   printf("OT time=%.3f sum=%.1f\n", GET_SEC(start, clock()), sum);

   sum = 0.0; start = clock();
   
   for(int i = 0; i < SIZE / 10000; i++)
      for(int k = 0; k < 10000; k++)
         sum += x[k * (SIZE / 10000) + i];

   printf("Ot time=%.3f sum=%.1f\n", GET_SEC(start, clock()), sum);

   sum = 0.0; start = clock();
   
   for(int i = 0; i < SIZE / 100000; i++)
      for(int k = 0; k < 100000; k++)
         sum += x[k * (SIZE / 100000) + i];

   printf("Oh time=%.3f sum=%.1f\n", GET_SEC(start, clock()), sum);
}