complex vector addition using structures in c - c

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++)
{
...
}

Answer 2

At first, your program stops at the line *aaa.re = 5;
int main()
{
vect_complex aaa;
vect_complex bbb;
*aaa.re = 5; //your program stops here.
....
}
The reason is that you defined structure aaa which allocates memory for double pointer re and im , NOT for the double values.
As of now these pointers will point to uninitialized value. when you refer like *aaa.re ie) when you dereference it, you will get segmentation fault.
For example, aaa.re points to 0x17 in my box. when i dereference it, am getting segmentation fault, since it is referring the memory address which is out of program memory area.
To resolve this problem, you should allocate the memory for double and store the address
of it into the pointer re. Then store the double value.
Brain covered Other details perfectly.
Thanks,
nvseenu