PVS-Studio warning V550 for CPU Identifying Tool

void projillum(short* wtab, int xdots, int ydots, double dec)
{
  ...
  s = sin(-dtr(dec));
  x = -s * sin(th);
  y = cos(th);
  ...
  lon = (y == 0 && x == 0) ? 0.0 : rtd(atan2(y, x));
}

It's strange to expect 'x' and 'y' to exactly equal 0 after all these calculations.

This suspicious code was found in CPU Identifying Tool project by PVS-Studio static code analyzer.
Warning message is:
V550 An odd precise comparison: x == 0. It's probably better to use a comparison with defined precision: fabs(A - B) '<' Epsilon. clock_dll sunalgo.cpp 155

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/