annotate src/samer/units/Matrices.java @ 8:5e3cbbf173aa tip

Reorganise some more

/*
 *	Copyright (c) 2000, Samer Abdallah, King's College London.
 *	All rights reserved.
 *
 *	This software is provided AS iS and WITHOUT ANY WARRANTY; 
 *	without even the implied warranty of MERCHANTABILITY or 
 *	FITNESS FOR A PARTICULAR PURPOSE.
 */

package samer.units;
import  samer.core.*;
import  samer.maths.*;

/** Some special matrix factories */
public class Matrices
{
	public static void set(Matrix A, Generator G) { A.set(G); A.changed();	}
	public static void add(Matrix A, Generator G) { A.add(G); A.changed(); }
	
	public static void fourierBasis(Matrix A)
	{
		int m=A.getColumnDimension();
		int n=A.getRowDimension();
		double [][] a = A.getArray();

		for (int j=3; j<m;j+=2) {
			double omega=(j-1)*Math.PI/m;
			for (int i=0; i<n; i++) {
				double theta=i*omega;
				a[i][j-2] = Math.cos(theta);
				a[i][j-1] = Math.sin(theta);
			}
		}
		for (int i=0; i<n; i++) {
			a[i][0]   = 1;
			a[i][m-1] = (i%2)==0 ? 1 : -1;
		}
		A.changed();
	}

	public static void pingBasis(Matrix A) {
		pingBasis(A,Shell.getDouble("gamma",0.5));
	}

	public static void pingBasis(Matrix A, double gamma)
	{
		int extra = (int)(3.0*16.0/gamma);
		int m=A.getColumnDimension();
		int n=A.getRowDimension();
		double [][] a = A.getArray();

		A.zero();

		for (int j=0; j<m; j++) {
			int jj=(int)((n+extra)*Math.random())-extra;
			double omega=0.2+2*Math.random();
			double t=0.0;
			for (int i=0; i<n; i++) {
				if (i>=jj) {
					t=i-jj;
					a[i][j]=Math.exp(-gamma*t/16)*Math.sin(omega*t);
				} else a[i][j]=0;
			}
		}
		A.changed();
	}

	public static void fuzzyIdentity(Matrix matrix) {
		int		n = matrix.getRowDimension();
		int		m = matrix.getColumnDimension();
		fuzzyIdentity(matrix,Shell.getDouble("sigma",
			(n>m) ? n/(double)m : m/(double)n));
	}

	public static void fuzzyIdentity(Matrix matrix, double s) 
	{
		int		n = matrix.getRowDimension();
		int		m = matrix.getColumnDimension();
		double	t = s/Math.max(n,m);
		double	I[][] = matrix.getArray();

		for (int i=0; i<n; i++) {
			for (int j=0; j<m; j++) {
				double Z = j/(double)(m-1) - i/(double)(n-1);
				I[i][j] = Math.exp(-(Z*Z)/(2*t*t));
			}
		}

		matrix.changed();
	}
}