Example 3: Solve a Small Linear System Stored in Sparse Form

using System;
using Imsl.Math;
public class GenMinResEx3 : GenMinRes.IFunction
{
    private static SparseMatrix A;
    private static double[] a = {6.0, 10.0, 15.0, -3.0, 10.0, -1.0, 
                                -1.0, -3.0, -5.0, 1.0, 10.0, -1.0, 
                                -2.0, -1.0, -2.0};
    private static int[] irow = {5, 1, 2, 1, 3, 3, 4, 4, 4, 4, 0, 5, 5, 1, 3};
    private static int[] jcol = {5, 1, 2, 2, 3, 4, 0, 5, 3, 4, 0, 0, 1, 3, 0};
    private static double[] b = {10.0, 7.0, 45.0, 33.0, -34.0, 31.0};
    private static double[] xguess = {1.0, 1.0, 1.0, 1.0, 1.0, 1.0};
    
    public void  Amultp(double[] p, double[] z)
    {
        double[] result;
        result = Imsl.Math.SparseMatrix.Multiply(A, p);
        Array.Copy(result, 0, z, 0, z.Length);
    }
    
    public static void  Main(String[] args)
    {
        int n = 6;
        
        A = new SparseMatrix(n, n);
        for (int i = 0; i < a.Length; i++)
        {
            A.Set(irow[i], jcol[i], a[i]);
        }
        
        GenMinResEx3 atp = new GenMinResEx3();
        
        // Construct a GenMinRes object
        GenMinRes gnmnrs = new GenMinRes(n, atp);
        gnmnrs.SetGuess(xguess);
        // Solve Ax = b
        new PrintMatrix("x").Print(gnmnrs.Solve(b));
    }
}

Output

  x
   0  
0  1  
1  2  
2  3  
3  4  
4  5  
5  6