GenMinRes Simple Example

Example 1: Solve a Small Linear System

A solution to a small linear system is found. The coefficient matrix is stored as a full matrix and no preconditioning is used. Typically, preconditioning is required to achieve convergence in a reasonable number of iterations.

import com.imsl.math.*;
import com.imsl.Messages;
import com.imsl.IMSLException;

public class GenMinResEx1 implements GenMinRes.Function {
	static private double a[][] = {
            {33.0,   16.0,  72.0},
            {-24.0, -10.0, -57.0},
            {18.0,  -11.0,   7.0}
        };
        static private double	b[] = {129.0, -96.0, 8.5};
        // If A were to be read in from some outside source the   //
        // code to read the matrix could reside in a constructor. //

    public void amultp(double p[], double z[]) {
        double [] result;
        result = Matrix.multiply(a,p);
        System.arraycopy(result,0,z,0,z.length);
    }

    public static void main(String args[]) throws Exception {
        int       n = 3;
        
        GenMinResEx1 atp = new GenMinResEx1();
        
        // Construct a GenMinRes object
        GenMinRes gnmnrs = new GenMinRes(n, atp);

        // Solve Ax = b
        new PrintMatrix("x").print(gnmnrs.solve(b));     
    }
}

Output

Link to Java source.