public static double first(double a, Form1.one only_one) { return((only_one(a + dx) - only_one(a)) / dx); }
public static double second(double a, double first, Form1.one only_one) { return((first - (only_one(a) - only_one(a - dx)) / dx) / dx); }
public static double first(double a, Form1.one only_one) { return((only_one(a + dx) - only_one(a)) / dx); }
public static double second(double a, double first, Form1.one only_one) { return((first - (only_one(a) - only_one(a - dx)) / dx) / dx); }