Example 1: Integral $\int_1^3 e^{2x} \, dx$

The integral $\int_1^3 e^{2x} \, dx$ is computed and compared to its expected value.

import com.imsl.math.*;

public class QuadratureEx1 {
    public static void main(String args[]) {
        Quadrature.Function fcn = new Quadrature.Function() {
            public double f(double x) {
                return Math.exp(2.*x);
            }
        };
        
        Quadrature q = new Quadrature();
        double result = q.eval(fcn, 1.0, 3.0);
        
        double expect = (Math.exp(6)-Math.exp(2))/2.;
        System.out.println("result = "+result);
        System.out.println("expect = "+expect);
    }
}

Output

result = 198.01986869690225
expect = 198.01986869690222

Link to Java source.