matrix multiplication can't be compile - c

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
sekuensial.c(16): error C2143: syntax error : missing ')' before
'type'
sekuensial.c(16): error C2198: 'randomMatriks' : too few arguments
for call
sekuensial.c(16): error C2059: syntax error : ')'
sekuensial.c(29): error C2059: syntax error : '%'
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