GenMinRes Simple Example With Logging

Example 7: Solve a Small Linear System With Logging

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. Logging is enabled so that intermediate output and a summary report are generated.

import com.imsl.math.*;
import com.imsl.Messages;
import com.imsl.IMSLException;
import java.util.logging.Logger;
import java.util.logging.LogRecord;
import java.util.logging.Level;
import java.util.logging.Handler;
public class GenMinResEx7 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;
        
        GenMinResEx7 atp = new GenMinResEx7();
        
        // Construct a GenMinRes object
        GenMinRes gnmnrs = new GenMinRes(n, atp);
        Logger logger = gnmnrs.getLogger();
        Handler h = new java.util.logging.FileHandler("GenMinReslog.txt");
        logger.addHandler(h);
        logger.setLevel(Level.FINER);
        h.setFormatter(new GenMinRes.Formatter());  
        // Solve Ax = b
        new PrintMatrix("x").print(gnmnrs.solve(b));     
    }
}

Output

Link to Java source.