cuComplex.h and exp()

Question

Q0:

Is exp() supported by cuComplex.h?

Q1:

How to write A = B * exp(i * C), where A, B, C are same size arrays of real numbers? Is this right?

ma

Answer 1

cuComplex.h only offers some basic operations on cuComplex (principally those used inside the CUBLAS and CUFFT libraries), the exponential function is not supported.

You can implement the exponential yourself using component-wise arithmetic. cuComplex stores the real part of a complex number in the x component and the imaginary part in the y component. Given a complex number z = x + i*y, the exponent can be computed as:

exp(z) = exp(x) * (cos(y) + i * sin(y))

This leads to the following CUDA code (untested):

cuComplex my_complex_exp (cuComplex arg)
{
   cuComplex res;
   float s, c;
   float e = expf(arg.x);
   sincosf(arg.y, &s, &c);
   res.x = c * e;
   res.y = s * e;
   return res;
}