指针索引c语言,指针，内存分配：矩阵乘法中的行索引(C编程)

我无法理解问题所指的“行的索引”是什么意思......你能给我一个例子吗？为什么

sum = sum + a[(row * a_cols) + k] * b[k * b_cols + col]?谢谢！

double dotProduct(double a[], const unsigned a_rows, const unsigned a_cols,

/* a is a matrix with a_rows rows and a_cols columns */

double b[], const unsigned b_cols,

/* b is also a matrix. It has a_cols rows and b_cols columns */

unsigned row, // an **index of a row of a**

unsigned col) // an index of a column of b

{

int k; // loop variable

double sum = 0.0; // the result of the dot product is stored here

k = 0;

while (k < a_cols) { // recall: a_cols == b_rows

/* we need to multiply a[row, k] and b[k, col] and add that to sum */

sum = sum + a[(row * a_cols) + k] * b[k * b_cols + col];

/* recall a[i,j] is stored at a[(i * a_cols) + j]

and b[i,j] is stored at b[(i * b_cols) + j] */

k += 1;

}

return sum;

}