C/C++ VS. Fortran

C/C++  VS.  Fortran
项目	C/C++	Fortran	备注
软硬件环境	操作系统：Windows XP professional 2002 Service Pack 3 CUP：Intel® Core™2 Quad 2.66GHz  4核 内存：3.00GB
编译环境	VS2008	Intel Fortran Compler Xe 2011+MKL
浮点型循环比较	#include <time.h> #include <iostream> using namespace std; int main() {  clock_t start, end;  int i,j,k;  double m;  start = clock();  m=0.0;  for (i=1;i<=1000;i++)  {   for (j=1;j<=1000;j++)   {    for (k=1;k<=1000;k++)    {     m=m+1.0;    }   }  }  end = clock();  printf("Time was: %f\n", (double)(end-start)/CLOCKS_PER_SEC);  printf("Result is: %f\n", m);  char a;  cin>>a;  return 0; } 耗时：1.125s	PROGRAM CPUTIME          IMPLICIT NONE          REAL time_begin, time_end          INTEGER I, J, K          REAL(8) M          CALL CPU_TIME ( TIME_BEGIN )          M=0.0_8          DO I=1,1000                  DO J=1,1000                          DO K=1,1000                          M=M+1.0_8                          END DO                  END DO          END DO          CALL CPU_TIME ( TIME_END )          PRINT *, 'TIME WAS ', time_end - time_begin          PRINT *, 'Result is ', M          pause END PROGRAM CPUTIME 耗时：1.125s	在release版本下比较
整型循环比较 （带数据转换）	#include <time.h> #include <iostream> using namespace std; int main() {  clock_t start, end;  int i,j,k;  int m;  start = clock();  m=0;  for (i=1;i<=1000;i++)  {   for (j=1;j<=1000;j++)   {    for (k=1;k<=1000;k++)    {     m=m+1*2.0;    }   }  }  end = clock();  printf("Time was: %f\n", (double)(end-start)/CLOCKS_PER_SEC);  printf("Result is: %d\n", m);  char a;  cin>>a;  return 0; } 耗时：8.734s	PROGRAM CPUTIME          IMPLICIT NONE          REAL time_begin, time_end          INTEGER I, J, K          INTEGER M          CALL CPU_TIME ( TIME_BEGIN )          M=0          DO I=1,1000                  DO J=1,1000                          DO K=1,1000                          M=M+1*2_8                          END DO                  END DO          END DO          CALL CPU_TIME ( TIME_END )          PRINT *, 'TIME WAS ', time_end - time_begin          PRINT *, 'Result is ', M          pause END PROGRAM CPUTIME 耗时：0.515625s	在release版本下比较
矩阵乘法比较1 （矩阵大小1048576*80）	#include <time.h> #include <iostream> using namespace std; int main() {  clock_t start, end;  int i,j,k;  const int rows=1024*1024;  const int cols=80;  const int count=rows*cols;  float *x=new float[rows*cols];  float c[cols][cols];  for (i=0;i<count;i++){   x[i]=1.0f; }  start = clock();  for (i=0;i<cols;i++) {   for (j=0;j<cols;j++)  {    float sum=0;    for (k=0;k<rows;k++){     sum+=x[k*cols+i]*x[k*cols+j];   }    c[i][j]=sum;  } }  end = clock();  printf("Time was: %f\n", (double)(end-start)/CLOCKS_PER_SEC);  printf("Result is: %f\n", c[1][1]);  char a;  cin>>a;  return 0; } 耗时：165.735s	不使用MKL库： PROGRAM CPUTIME      IMPLICIT NONE      real :: x(1024*1024,80)      real :: c(80,80)      real :: sum_t      integer :: i,j,k      integer,parameter:: count=1024*1024      REAL time_begin, time_end                  x=1          CALL CPU_TIME ( TIME_BEGIN )             do i=1,80             do j=1,80                 sum_t=0_4;                 do k=1,count                     sum_t=sum_t+x(k,i)*x(k,j)                 end do                 c(i,j)=sum_t             end do        end do          CALL CPU_TIME ( TIME_END )          print *,c      PRINT *, 'TIME WAS ', time_end - time_begin      pause END PROGRAM CPUTIME 耗时：8.25s	在release版本下比较
矩阵乘法比较2 （矩阵大小1048576*80）	转置矩阵后相乘： #include <time.h> #include <iostream> using namespace std; int main() {  clock_t start, end;  int i,j,k;  const int rows=1024*1024;  const int cols=80;  const int count=rows*cols;  float *x=new float[rows*cols];  float c[cols][cols];  for (i=0;i<count;i++){   x[i]=1.0f; }  start = clock();  for (i=0;i<cols;i++) {   for (j=0;j<cols;j++)  {    float sum=0;    for (k=0;k<rows;k++){     sum+=x[i*rows+k]*x[j*rows+k];   }    c[i][j]=sum;  } }  end = clock();  printf("Time was: %f\n", (double)(end-start)/CLOCKS_PER_SEC);  printf("Result is: %f\n", c[1][1]);  char a;  cin>>a;  return 0; } 耗时：23.407s	使用MKL库： PROGRAM CPUTIME use mkl95_blas, only: gemm          IMPLICIT NONE          real :: x(1024*1024,80)          real :: c(80,80)          REAL time_begin, time_end                  x=1                  CALL CPU_TIME ( TIME_BEGIN )                  call gemm(x, x, c, 'T', 'N', 1.0, 0.0)                  CALL CPU_TIME ( TIME_END )                  print *,c          PRINT *, 'TIME WAS ', time_end - time_begin                  pause END PROGRAM CPUTIME 耗时：1.3125s	在release版本下比较
总结	1、从单纯的循环操作来看C/C++与Fortran的性能不相上下，但是从数值计算方面来看Fortran比C还是有比较大的优势的，如果使用MKL那优势就更明显了； 2、从对矩阵操作的代码上来看Fortran比C要更简洁一些，但是在Fortran中调用函数的操作会比较复杂一些。