private const double sqrln = 0.600561204393225; // 1 / (2 * Math.Sqrt(Math.Log(2)) )
unsafe private static double F(double intensity, double tau, double fwhm, int channel, double scale, double x0)
{
double s = fwhm * sqrln;
double t = (channel + x0) * scale;
return(intensity / 2 * (Y(tau, s, t) - Y(tau, s, t + scale) -
Erf.erfc((t + scale) / s) + Erf.erfc(t / s)));
}
unsafe private static double Y(double tau, double s, double t)
{
return(Math.Exp(s * s / 4 / tau / tau) * Erf.erfc(s / 2 / tau - t / s) * Math.Exp(-t / tau));
}
