Auxiliary Data Transformations

This section presents C examples for conversion from the Cartesian to polar representation of complex data and vice versa.

// Cartesian->polar conversion of complex data
// Cartesian representation: z = re + I*im
// Polar representation: z = r * exp( I*phi )
#include <mkl_vml.h>
 
void 
variant1_Cartesian2Polar(int n,const double *re,const double *im,
                         double *r,double *phi)
{
    vdHypot(n,re,im,r);         // compute radii r[]
    vdAtan2(n,im,re,phi);       // compute phases phi[]
}
 
void 
variant2_Cartesian2Polar(int n,const MKL_Complex16 *z,double *r,double *phi,
                         double *temp_re,double *temp_im)
{
    vzAbs(n,z,r);               // compute radii r[]
    vdPackI(n, (double*)z + 0, 2, temp_re);
    vdPackI(n, (double*)z + 1, 2, temp_im);
    vdAtan2(n,temp_im,temp_re,phi); // compute phases phi[]
}

// Polar->Cartesian conversion of complex data.
// Polar representation: z = r * exp( I*phi )
// Cartesian representation: z = re + I*im
#include <mkl_vml.h>
 
void
variant1_Polar2Cartesian(int n,const double *r,const double *phi,
                         double *re,double *im)
{
    vdSinCos(n,phi,im,re);      // compute direction, i.e. z[]/abs(z[])
    vdMul(n,r,re,re);           // scale real part
    vdMul(n,r,im,im);           // scale imaginary part
}
 
void
variant2_Polar2Cartesian(int n,const double *r,const double *phi,
                         MKL_Complex16 *z,
                         double *temp_re,double *temp_im)
{
    vdSinCos(n,phi,temp_im,temp_re); // compute direction, i.e. z[]/abs(z[])
    vdMul(n,r,temp_im,temp_im); // scale imaginary part
    vdMul(n,r,temp_re,temp_re); // scale real part
    vdUnpackI(n,temp_re,(double*)z + 0, 2); // fill in result.re
    vdUnpackI(n,temp_im,(double*)z + 1, 2); // fill in result.im
}