Thread: Matrix vector multiplication using function

Hi everybody,
What is wrong with the program below? it is supposed to multiply a matrix by vector.

Code:

 
#include <iostream>

using namespace std;

void matris_muller(double a[][3], double x[3],double *b);

int main(){

double a_cap[][3] = {1,0,0,0,2,0,0,0,3};
double x[3] = {1,1,1};
double *b1;
matris_muller(a_cap , x , b1);

for (int i = 0 ; i <= 2; ++i)
    cout<<"  "<<b1[i]<<endl;

}

void matirs_muller(double a[][3], double x[3],double *b){

for(int i = 0 ; i <= 2 ; ++i){
    for(int j = 0 ; j <=  2; ++j){


        b[j] += a[i][j] * x[j];
    }
}

}