I have started using gsl recenltly in a huge old C project. I have managed to add the libraries by adding the location in my system in **Properties>C/C++>General>Additional Include Directories**.

In my code, I am also including the following:

```
#include "gsl/gsl_matrix.h"
#include "gsl/gsl_matrix_complex_double.h"
#include "gsl/gsl_matrix_complex_float.h"
#include "gsl/gsl_matrix_complex_long_double.h"
#include "gsl/gsl_math.h"
#include "gsl/gsl_spmatrix.h"
#include "gsl/gsl_complex.h"
#include "gsl/gsl_complex_math.h"
#include "gsl/gsl_inline.h"
#include "gsl/gsl_complex.h"

```

I can now use most functions of gsl. but in the fowllowing function:

```
void vector_complex_mul_elements(gsl_vector_complex *v1, gsl_vector_complex *v2)
{
    gsl_complex cpx1, cpx2, cpx3;
    GSL_SET_COMPLEX(&cpx1, 0, 0);
    GSL_SET_COMPLEX(&cpx2, 0, 0);
    GSL_SET_COMPLEX(&cpx3, 0, 0);

    if(v1->size != v2->size)
    {
        printf("Error: Lenght of arrays do not match.\n");
        return;
    }

    for(i=0; i < v1->size; i++)
    {
        cpx1 = gsl_vector_complex_get(v1, i);
        cpx2 = gsl_vector_complex_get(v2, i);
        //cpx3 = gsl_complex_mul(cpx1 , cpx2);
        gsl_vector_complex_set(v1, i, cpx3);

    }
}

```

When I uncomment the line:

```
cpx3 = gsl_complex_mul(cpx1 , cpx2);

```

I get the following errors:

> 
> Error LNK2001: Unresolved external symbol "\_log1p".
> 
> 
> Error LNK2001: Unresolved external symbol "\_log1p".
> 
> 
> Error LNK2001: Unresolved external symbol "\_hypot".
> 
> 
> Error LNK1120: 2 unresolved external references.
> 
> 
> 

I have already tried writing it like:

```
gsl_vector_complex_set(v1, i, gsl_complex_mul(cpx1 , cpx2));

```

Then I get these errors:

> 
> Error LNK2019: Reference to unresolved external symbol "\_log1p" in function "\_gsl\_complex\_logabs".
> 
> 
> Error LNK2019: Reference to unresolved external symbol "\_hypot" in function "\_gsl\_complex\_div".
> 
> 
> Error LNK2001: Unresolved external symbol "\_log1p".
> 
> 
> Error LNK1120: 2 unresolved external references.
> 
> 
> 

Is this a only a linking problem or the way I am using it is wrong?