Question

I am trying to do complex vector addition and dot product using structures in C for a project. I have my code written, however, while it is compiling without a problem, once i run my program it stops working. I have other parts to the program but this is only the relevant part. I am also trying to do matrix addition and multiplication with complex numbers. I think I can modify the others if I can get these working. Any help at all would be appreciated. Thanks, I appreciate it.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#define PI 3.14159265359

typedef struct complex
{
    double re;
    double im;
}complex;

typedef struct vect_complex
{
    double *re;
    double *im;
}vect_complex;

typedef struct mat_complex
{
    //int i=0,j=0;
    double re[100][100];
    double im[100][100];
}mat_complex;

void vector_add(vect_complex a[4], vect_complex b[4], vect_complex c[4])
{
    int i;
    for(i=0; i<3 ;i++);
    {
        c->re[i] = a->re[i] + b->re[i];
        c->im[i] = a->im[i] + b->im[i];
    }
    printf("Vector addition = (%f + %f*j)i + (%f +%f*j)j + (%f + %f*j)k\n\n",c-    >re[0],c->im[0],c->re[1],c->im[1],c->re[2],c->im[2]);
}

void addmx(mat_complex *a, mat_complex *b, mat_complex *c)
{
    int  i, j;
    for ( i = 0 ; i < '\0' ; i++ )
    {
        for ( j = 0 ; j < '\0' ; j++ )
        {
            c->re[i][j] = a->re[i][j] + b->re[i][j];
            c->im[i][j] = a->im[i][j] + b->im[i][j];
        }
    }
    printf("***Matrix Addition***\n");
    for ( i = 0 ; i < '\0' ; i++ )
    {
        for ( j = 0 ; j < '\0' ; j++ )
        {
            printf("(%f + %f*j)   ", c->re[i][j],c->im[i][j]);
        }
        printf("\n");
    }
}

int main()
{
vect_complex aaa;
vect_complex bbb;
*aaa.re = 5;
*aaa.im = 4;
*bbb.re = 3;
*bbb.im = 2;
vect_complex ccc;

vector_add(&aaa, &bbb, &ccc);
vector_dot_prod(&aaa, &bbb, &ccc);

return 0;
}

Answer 1

There are a number of issues to deal with here.

1. vect_complex

Perhaps you’d like your vect_complex to hold a fixed number of elements, in which case it should be defined:

typedef struct vect_complex
{
    double re[3];
    double im[3];
} vect_complex;

Alternatively, you can keep your current definition but you will need to allocate new arrays every time you use the structure:

int main(void)
{
    vect_complex vc;

    vc.re = (double *) malloc(3 * sizeof(double));
    vc.im = (double *) malloc(3 * sizeof(double));

    vc.re[0] = 1.0;
    vc.im[0] = 2.0;
    ...
}

2. vector_add

This function should be taking references to vect_complex as inputs, not arrays of complex vectors. This implementation assumes the definition of vect_complex I gave above.

void vector_add(vect_complex * a, vect_complex * b, vect_complex * result)
{
    int i;
    for (i = 0; i < 3; i++)
    {
        result->re[i] = a->re[i] + b->re[i];
        result->im[i] = a->im[i] + b->im[i];
    }
}

3. addmx

I’m not sure what the '\0's are doing here. Change it to

for (i = 0; i < 100; i++)
    for (j = 0; j < 100; j++)
    {
        ...
    }