# include <stdio.h>
# include <math.h>

double newton(double f(double), double xo, int cit, int numit) {
    if (numit == cit) return xo;
    xo -= (f(xo) / d(f, xo));
    return newton(f, xo, numit, ++cit);
}

double f(double x) {
    return 2*pow(x, 2) - 2;
}

double d(double f(double), double x) {
    double h = pow(10, -9);
    return (f(x+h) - f(x))/h;
}

int main() {
    printf("%f\n", newton(f, 2.0, 1, 5));
    return 0;
}

// debian@debian~/Documents/dev/c/calculo: gcc calculo.c -o calculo.o -lm;chmod +x calculo.o
// debian@debian~/Documents/dev/c/calculo: ./calculo.o
// 1.000000