有關矩陣的運算請參考:http://www2.edu-edu.com.cn/lesson_crs78/self/j_0022/soft/ch0605.html
//矩陣乘法A*B
/*
矩陣相乘的條件:前面矩陣的列數等於後面矩陣的行數(對應這裏的na=mb)
A:ma*na B:mb*nb
C=A*B: ma*nb
*/
#include<stdio.h>
#include<stdlib.h>
int main()
{
int ma,na,mb,nb,i,j,k;
int t=0;
int **A,**B,**C;
int m,n,p;
printf("(Matrix A)Input ma and na\n");
scanf("%d%d",&ma,&na);
A=(int**)malloc(ma*sizeof(int*));
for(i=0;i<ma;i++)
A[i]=(int*)malloc(na*sizeof(int));//Initial A(爲矩陣A分配空間)
/*----------------------------------------------*/
printf("Input A:\n");
for(i=0;i<ma;i++)
for(j=0;j<na;j++)
scanf("%d",&A[i][j]);//Input A
/*----------------------------------------------*/
printf("(Matrix B)Input mb and nb\n");
scanf("%d%d",&mb,&nb);
B=(int**)malloc(mb*sizeof(int*));
for(i=0;i<mb;i++)
B[i]=(int*)malloc(nb*sizeof(int));//Initial B(爲矩陣B分配空間)
/*----------------------------------------------*/
printf("Input B:\n");
for(i=0;i<mb;i++)
for(j=0;j<nb;j++)
scanf("%d",&B[i][j]);//Input B
/*----------------------------------------------*/
printf("matrix A:\n");
for(i=0;i<ma;i++)
{
for(j=0;j<na;j++)
printf("%d ",A[i][j]);
printf("\n");
}//Output A
/*----------------------------------------------*/
printf("matrix B:\n");
for(i=0;i<mb;i++)
{
for(j=0;j<nb;j++)
printf("%d ",B[i][j]);
printf("\n");
}//Output B
/*----------------------------------------------*/
/*----------------------------------------------*/
m=ma;
n=nb;
p=mb;//p保存A的列數和B的行數
printf("m:%d n:%d\n",m,n);
C=(int**)malloc(m*sizeof(int*));
for(i=0;i<m;i++)
C[i]=(int*)malloc(n*sizeof(int));//Initial C=A*B(爲矩陣C分配空間)
/*----------------------------------------------*/
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
{
C[i][j]=0;
for(k=0;k<p;k++)
C[i][j]+=A[i][k]*B[k][j];//計算矩陣相乘的要點(循環內累加)
}
}//Calculate C=A*B
/*----------------------------------------------*/
printf("matrix C=A*B:\n");
for(i=0;i<m;i++)
{
for(j=0;j<n;j++)
printf("%d ",C[i][j]);
printf("\n");
}//Output C=A*B
return 0;
}