MIDI to frequency conversions

midifreq.c

double midi2freq(int midi)
{
  double f;

  f = exp (log (440.0) + (double)(midi - 69) * log (2.0) / 12.0);
  return (f);
}

int freq2midi(double f)
{
  int midi;

  midi = (int)(0.5 + 69.0 + 12.0 / log (2.0) * log (f / 440.0));
  return (midi);
}