protected double[] exp(AppMath.BaseFunc F, double x0, double x1)
{
double[] a = new double[4];
double x0_x1=(x0 - x1);
double LogF0_F1=Math.Log(F.Val(x0) / F.Val(x1));
double d = a[3] = (F.Diff(x1) / F.Val(x1) + F.Diff(x0) / F.Val(x0)+2*LogF0_F1/(x1-x0))/Math.Pow(-1*x0_x1,2);
double c = a[2] = ((2 * x0 * x0 - x0 * x1 - x1 * x1) * a[3] - F.Diff(x0) / F.Val(x0) - LogF0_F1 / (-1 * x0_x1)) / (-1 * x0_x1);
double b = a[1] = 1 / (x1 - x0) * (Math.Log(F.Val(x1) / F.Val(x0)) - a[3] * (Math.Pow(x1, 3) - Math.Pow(x0, 3)) - c * (Math.Pow(x1, 2) - Math.Pow(x0, 2)));
//A
a[0] = F.Val(x0) * Math.Exp(-1*(d * Math.Pow(x0, 3) + c * Math.Pow(x0, 2) + b * x0));
return a;
}