How do I calculate the length of hypotenuse?

Hypot is a mathematical function defined to calculate the length of the hypotenuse of a right-angle triangle. It was designed to avoid errors arising due to limited precision calculations performed on computers.

The Math.hypot(double x, double y) return the sqrt(x2 + y2) without intermediate overflow or underflow. The result will be same with this calculation
Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2)).

package org.kodejava.example.math;

public class HypotExample {
    public static void main(String[] args) {
        double number1 = 3.0d;
        double number2 = 5.0d;

        //
        // calculate square root of total value of
        // number1 ^ 2 + number2 ^ 2
        //
        double sqr = Math.hypot(number1, number2);

        System.out.println("Total value= " + (Math.pow(number1, 2) +
                Math.pow(number2, 2)));
        System.out.println("Square root= " + sqr);

    }
}

How do I calculate exponential function?

In mathematics, the exponential function is the function ex, where e is the number (approximately 2.718281828) such that the function ex equals its own derivative. The function f(x) = ex at the point x = 0 is equal to 1.

package org.kodejava.example.math;

public class ExponentExample {

    public static void main(String[] args) {
        double x = 0.0d;

        //
        // calculates e raised to the power of x (e^x)
        //
        double fx = Math.exp(x);

        //
        // calculates e raised to the power of x minus 1 (e^x - 1)
        //
        double fxm1 = Math.expm1(x);

        System.out.println("fx  = " + fx);
        System.out.println("fxm1= " + fxm1);
    }
}