c - 使用c中的结构对数组进行变量赋值的问题

Question

所以我正在尝试用 c 语言乘以矩阵。但是，当我尝试将两个数组中的数字相乘，并将它们放入答案数组时，它始终为零。这是该方法的代码，谢谢。

我的矩阵结构:

typedef struct matrix {
 int r;
 int c;
 double **mat;
 } *matrix_t;

我的矩阵乘法:

matrix_t mat_mult(matrix_t a, matrix_t b)
{
 int i, j, k;
 double x, temp1, temp2;
 double tempsol = 0.0;
 x = temp1 = temp2 = 0;
 matrix_t answer;

 if(a -> c == b -> r)
 {
    answer = mat_new(a -> r, b -> c);

    for(i = 0; i < a -> r; i++) 
       for( j = 0; j < b -> c; j++)
       {

           for( k = 0; k < a -> c; k++)
           {
               tempsol += a->mat[i][k] * b->mat[k][j];
               answer-> mat[i][j] =  tempsol;
           }

       }

 return answer;
 }
 else if(a -> r == b -> c)
 {
  answer = mat_new(a -> c, b -> r); 
  return answer;
 }
 else
 {
  printf("Matrices could not be multiplied");
  exit(1);
  return;
 }
}

这也是我的 mat_new 的代码

matrix_t mat_new(int r,int c)
{
int i = 0;
double **a;
matrix_t matrix_a;  

a = (double**)malloc(r *sizeof(double *));
for(i = 0; i < r; i++)
{
    a[i] = (double*)malloc(c *sizeof(double));
}
matrix_a = (matrix_t) malloc ( sizeof(struct matrix));
matrix_a -> mat = a;
matrix_a -> r = r;
matrix_a -> c = c;

return matrix_a;
}

Answer 1

您需要释放您的对象。您需要重置 tempsol。但最重要的是，您需要检查您的 mat_mult()。

matrix_t mat_mult(matrix_t a, matrix_t b)
{
 /* ... */
 if(a -> c == b -> r)
 {
  /* ... */
 }
 else if(a -> r == b -> c)
 {
                                    /* BZZZZT!                 */
  answer = mat_new(a -> c, b -> r); /* BZZZZT! mat_mult(b, a); */
                                    /* BZZZZT!                 */
  return answer;
 }
 else
 {
  /* ... */
 }
}