## How do I calculate exponential function?

In mathematics, the exponential function is the function `e``x`, where `e` is the number (approximately 2.718281828) such that the function `e``x` equals its own derivative. The function `f(x) = e``x` 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);
}
}
``````

## How do I get the exponent of exponential function?

The exponential function is `f(x) = e``x`. The `Math.getExponent()` method is used to get the `x` value of the given parameter, in which the parameter is a result of exponential function calculation.

``````package org.kodejava.example.math;

public class GetExponent {
public static void main(String[] args) {
double fx = 1.0d;
float fx1 = 1.0f;

int x = Math.getExponent(fx);
System.out.println("Exponent  = " + x);

// argument in float
int xf = Math.getExponent(fx1);
System.out.println("Exponent1 = " + xf);
}
}
``````