Question

我想请求帮助测量下方矩阵乘法的执行时间。我在 Windows 运行代码。我尝试使用 < a href=" http://www. cplusplus.com/ reference/clibrary/ ctime/ " relation="nofollow" >time. h < / a >, 但无法测量。我要将计时器放在哪里?

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

void main()
{
    int m1[10][10],i,j,k,m2[10][10],add[10][10],mult[10][10],r1,c1,r2,c2;
    /*double dif;
    time_t start, end;*/

    printf("Enter number of rows and columns of first matrix MAX 10
");
    scanf("%d%d",&r1,&c1);
    printf("Enter number of rows and columns of second matrix MAX 10
");
    scanf("%d%d",&r2,&c2);
    if(r2==c1)
    {
        printf("Enter rows and columns of First matrix 
");
        printf("Row wise
");
        for(i=0;i<r1;i++)
        {
            for(j=0;j<c1;j++)
                scanf("%d",&m1[i][j]);
        }
        printf("You have entered the first matrix as follows:
");
        for(i=0;i<r1;i++)
        {
            for(j=0;j<c1;j++)
                printf("%d	",m1[i][j]);
            printf("
");
        }
        printf("Enter rows and columns of Second matrix 
");
        printf("Again row wise
");
        for(i=0;i<r2;i++)
        {
            for(j=0;j<c2;j++)
                scanf("%d",&m2[i][j]);
        }
        printf("You have entered the second matrix as follows:
");
        for(i=0;i<r2;i++)
        {
            for(j=0;j<c2;j++)
                printf("%d	",m2[i][j]);
            printf("
");
        }
        /*time (&start);*/
        printf("Now we multiply both the above matrix 
");
        printf("The result of the multiplication is as follows:
");
        /*a11xA11+a12xA21+a13xA31 a11xA12+a12xA22+a13xA32 a11xA13+a12xA23+a13xA33*/
        for(i=0;i<r1;i++)
        {
            for(j=0;j<c2;j++)
            {
                mult[i][j]=0;
                for(k=0;k<r1;k++)
                {
                    mult[i][j]+=m1[i][k]*m2[k][j];
                    /*mult[0][0]=m1[0][0]*m2[0][0]+m1[0][1]*m2[1][0]+m1[0][2]*m2[2][0];*/
                }
                printf("%d	",mult[i][j]);
            }
            printf("
");
            /*time (&end);
            dif (difftime (end, start);
            printf("Time of execution is : %f
",dif)*/
        }
        getch();
    }
    else
    {
        printf("Matrix multiplication cannot be done");
    }
}

我希望测量尽可能准确

Answer 1

我认为,你最好不要在您目前掌握的循环之外,在拨打 gache () 之前使用结束时间代码。这将给您最大的数数机会超过1秒。要获得一个体面的尺度, 您可能需要重复整个乘法的多次( 以便用10秒的秒来测量总时间) 。您也应该避免在循环中打印; 打印时间可能会主宰计算时间。

您剩下的麻烦是 time () fear () < a href=\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ \\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

Answer 2

the time function s precision, so if the code executes less than 1 second, you can t get correct output. On windows, I prefer to use GetTickCount

样本样本样本

#include "Windows.h"
int main (void)
{
  DWORD start,end;
  start = GetTickCount();
  //do something like Sleep(1000)
  end = GetTickCount();
  printf("elapse %d milliseconds
", end - start);
  return 0;
}

Answer 3

使用 block () 怎么样?

#include <stdio.h>
#include <math.h>
#include <assert.h>
#include <time.h>

int main() {
 clock_t start, stop;
 double t = 0.0;

 /* Start timer */ 
 start = clock();    
 assert(start != -1);

 /* Perform calculations */

 /* Stop timer */
 stop = clock();
 t = (double) (stop-start)/CLOCKS_PER_SEC; 
 printf("Run time: %f
", t);

 return(0);
} /* main */

友情链接