#define DX 0.0001 typedef double (*func)(double); double NthDeriv(int n, func f, double x) { if (n == 1) { return (f(x + DX) - f(x)

#define DX 0.0001 typedef double (*func)(double); double NthDeriv(int n, func f, double x) { if (n == 1) { return (f(x + DX) - f(x)) / DX; } else { return (NthDeriv(n - 1, f, x + DX) - NthDeriv(n - 1, f, x)) / DX; } } double Cube(double x) { return x * x * x; } double result = NthDeriv(3, &Cube, 5.0);