矩阵乘法无法编译

Question

I have some trouble when compiling this

#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <time.h>

int perkalianMatriks(double ** A, double ** B, double ** C, int n);
int randomMatriks(double * m, int n);

int main(int argc, char *argv[]) {
    int n_order = 0 , i, j;
    double ** A, ** B, ** C;
    time_t time1, time2;
    double diff_sec;

    randomMatriks(double * m, int n)

    A = (double **) malloc(sizeof(double) * n_order);
    B = (double **) malloc(sizeof(double) * n_order);
    C = (double **) malloc(sizeof(double) * n_order);

    for (i = 0; i < n_order; i++) {
        A[i] = (double *) calloc(sizeof(double), n_order);
        B[i] = (double *) calloc(sizeof(double), n_order);
        C[i] = (double *) calloc(sizeof(double), n_order);
    }

    printf("\nMatrix Sizes : ");
    scanf("%d", %n_order);


    time(&time1);
    perkalianMatriks(A, B, C, n_order);
    time(&time2);
    diff_sec = difftime (time2,time2);


    printf ("Total time to execute %f seconds.\n", diff_sec);
    return 0;
}

int randomMatriks(double * m, int n) {
    int i;

    for (i = 0; i < n_order; i++) {
        m[i] = (double) (rand() % 10) + 1;
    }
}

int perkalianMatriks(double ** a, double ** b, double ** c, int n) {
    int i, j, k;

    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            c[i][j]=0;          
            for (k = 0; k < n; k++)
            {
                c[i][j] += a[i][k] * b[k][j];
            }
        }
    }

    return 0;
}

Error when compiling

1. sekuensial.c(16): error C2143: syntax error : missing ')' before 'type'
2. sekuensial.c(16): error C2198: 'randomMatriks' : too few arguments for call
3. sekuensial.c(16): error C2059: syntax error : ')'
4. sekuensial.c(29): error C2059: syntax error : '%'
5. sekuensial.c(45): error C2065: 'n_order' : undeclared identifier

Does anyone can help me fix this?

Answer 1

You're missing a semi-colon. And you can't name a variable double . I guess this line should just be removed, since it is a cut and paste of the declaration above. If you need to call it, you should call it with real arguments. I don't see that you defined anything suitable for the first parameter, I guess from later on in your code, you intend to use n_order for the second parameter.

randomMatriks(double * m, int n)
              ^^^^^^            ^^^

This scanf is wrong, you probably want & :

scanf("%d", %n_order);
            ^^^

The variable dif_sec doesn't exist. Typo.

dif_sec = difftime (time2,time2);
^^^^^^^
printf ("Total time to execute %f seconds.\n", dif_sec);
                                               ^^^^^^^

The variable n_order doesn't exist. n instead probably.

for (i = 0; i < n_order; i++) {
                ^^^^^^^

The randomMatriks should return something. It falls off without a return statement, even though it is declared to return an int .

You have some unused variables and function parameters.

int main(int argc, char *argv[]) {
             ^^^^        ^^^^
    int n_order = 0 , i, j;
                         ^^^

Answer 2

The problem is that you never initialized your C array, which is an array of pointers to pointers to double. In perkalianMatriks , it's deferenced, and at that point, all bets are off as to what the pointer is (0xfdfdfdfd in your case).

(I'm guessing you might not understand what a ** type really is and how it's supposed to be used?)

Answer 3

That is not correct way of allocating memory for * B and so on. See example on allocating memory for double pointers ( *B) and so for the rest of pointers. Also take care of semi colons.

Answer 4

It is quite simple to perform multiplication of two matrices.

Your can get a simple clue at : solvedc.com