source: Deliverables/D4.1/GCC/Arctan.c @ 185

float fpow(float b, int r)
{
  if(r == 0)
    return 1.0f;
  else
    return b * fpow(b, r - 1);
}

float arctan(float x, int precision)
{
  int i;
  int m;
  float r;
  r = 0.0f;
  m = 1;
  for(i = 1; i <= precision; i += 2)
  {
    r += m * (fpow(x, i) / i);
    m *= -1;
  }
  return r;
}

int main()
{
  float f;
  // DPM: According to Google this is 0.785398163, but with this precision more
  // like 0.723 (according to GCC).
  f = arctan(1.0f, 7);
  if(f >= 0.7 && f <= 0.8)
    return 5;
  else
    return 7;
}