code: public static  cuDoubleComplex cuCadd (cuDoubleComplex x, cuDoubleComplex y)
      {
          return cuCmplx (cuCreal(x) + cuCreal(y), cuCimag(x) + cuCimag(y));
      }
docs: Returns a new complex number that is the sum of the given
  complex numbers.
  
  @param x The first addend
  @param y The second addend
  @return The sum of the given addends