import java.io.*;

public class Driver {
    /* Driver routine -- test out the code on a sample problem
     */
    public static void driver(int n, int maxiter, Sparse aMat, 
			      Preconditioner pMat)
    {
	try {
	    double [1d] b = new double [0:n-1];
	    double [1d] x = new double [0:n-1];
	    double [1d] rhist = new double [0:maxiter-1];

	    double rtol = 1e-3;

	    int i, retval;

	    DataOutputStream rhistOutFile = 
		new DataOutputStream(new FileOutputStream("rhist.out"));
	    DataOutputStream xOutFile = 
		new DataOutputStream(new FileOutputStream("x.out"));
	    b.set(1);

	    retval = CG.precondCG(aMat, pMat, b, x, rtol, n, rhist, maxiter);

	    for (i = 0; i < n; i++) {
		xOutFile.writeBytes(Double.toString(x[i]) + "\n");
	    }

	    int lastIter;
	    if (retval < 0) {
		lastIter = maxiter;
		System.out.println("Iteration failed to converge!\n");
	    } else {
		lastIter = retval;
		System.out.println("Converged after " + retval + " iterations.");
	    }
	    for (i = 0; i < lastIter; ++i) {
		rhistOutFile.writeBytes(Double.toString(rhist[i])+"\n");
	    }
	
	    rhistOutFile.close();
	    xOutFile.close();

	} catch (IOException e) {
	    System.out.println("Unable to open or use output files: " + e);
	    return;
	}
    }


    public static void main(String [] args)
    {
	int maxIter = 500;
	if (args.length <= 0 || Character.isDigit(args[0].charAt(0))) {   
	    int n;
	    if (args.length == 0) {
		n = 10;
	    } else {
		n = Integer.parseInt(args[0]);
	    }

	    System.out.println("Using default 1-d Poisson on a " + n + 
			       " point mesh.\n");
	    driver(n, maxIter, new Poisson1D(n), new IdentityPrecond());

	    System.out.println("Using 1-d Poisson on " + n + 
			       " point mesh with precond\n");
	    driver(n, maxIter, new Poisson1D(n), 
		   new Poisson1DBlockJacobiPrecond(n));
	} else {

	    CSR aMat;
	    try {
		aMat = MMIO.CSRLoad(args[0]); 
	    } catch (IOException e) {
		System.out.println(e);
		return;
	    }
	    System.out.println("Using problem " + args[0]);

	    System.out.println("Vanilla CG:        ");
	    driver(aMat.dim(), maxIter, aMat, new IdentityPrecond()); 
	}
    }
}