[Discuss-gnuradio] complex arithmetic

[David Carr]

Why does this die with:

gr_complex_mag.cc: In member function `virtual int gr_complex_mag::work(int,
  gr_vector_const_void_star&, gr_vector_void_star&)':
gr_complex_mag.cc:55: error: `cabs' undeclared (first use this function)

I've included <complex> and I think that the cabs function should be 
there.  The conj function works.  What am I missing?

Thanks,
David Carr

The file:
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <complex>

#include <gr_complex_mag.h>
#include <gr_io_signature.h>

gr_complex_mag::gr_complex_mag ()
 : gr_sync_block ("complex_mag",
          gr_make_io_signature (1, 1, sizeof (gr_complex)),
          gr_make_io_signature (1, 1, sizeof (float)))
{
}

gr_complex_mag_sptr
gr_make_complex_mag ()
{
 return gr_complex_mag_sptr (new gr_complex_mag ());
}

int
gr_complex_mag::work (int noutput_items,
                  gr_vector_const_void_star &input_items,
                  gr_vector_void_star &output_items)
{
 gr_complex *in = (gr_complex *) input_items[0];
 float *out = (float *) output_items[0];
  
 for (int i = 0; i < noutput_items; i++){
   //gr_complex product = in[i] * conj (in[i-1]);
   float ans = cabs (in[i]);
   //out[i] = conj(input_items[i]);
 }

 return noutput_items;
}