double N(double x)
{
return(0.5 * (1.0 + SpecialFunction.erf(x / Math.Sqrt(2.0))));
}
public double concX()
{
return(Math.Round((((1 - ((SpecialFunction.erf((((x / (2 * Math.Sqrt((d0 * Math.Exp(-qd / (r * (temp + 273.15)))) * time))))))))) *
(cs - c0)) + c0), 5));
}