samer@0: /*
samer@0:  *	Copyright (c) 2000, Samer Abdallah, King's College London.
samer@0:  *	All rights reserved.
samer@0:  *
samer@0:  *	This software is provided AS iS and WITHOUT ANY WARRANTY; 
samer@0:  *	without even the implied warranty of MERCHANTABILITY or 
samer@0:  *	FITNESS FOR A PARTICULAR PURPOSE.
samer@0:  */
samer@0: 
samer@0: package samer.units;
samer@0: import  samer.core.*;
samer@0: import  samer.maths.*;
samer@0: 
samer@0: /** Some special matrix factories */
samer@0: public class Matrices
samer@0: {
samer@0: 	public static void set(Matrix A, Generator G) { A.set(G); A.changed();	}
samer@0: 	public static void add(Matrix A, Generator G) { A.add(G); A.changed(); }
samer@0: 	
samer@0: 	public static void fourierBasis(Matrix A)
samer@0: 	{
samer@0: 		int m=A.getColumnDimension();
samer@0: 		int n=A.getRowDimension();
samer@0: 		double [][] a = A.getArray();
samer@0: 
samer@0: 		for (int j=3; j<m;j+=2) {
samer@0: 			double omega=(j-1)*Math.PI/m;
samer@0: 			for (int i=0; i<n; i++) {
samer@0: 				double theta=i*omega;
samer@0: 				a[i][j-2] = Math.cos(theta);
samer@0: 				a[i][j-1] = Math.sin(theta);
samer@0: 			}
samer@0: 		}
samer@0: 		for (int i=0; i<n; i++) {
samer@0: 			a[i][0]   = 1;
samer@0: 			a[i][m-1] = (i%2)==0 ? 1 : -1;
samer@0: 		}
samer@0: 		A.changed();
samer@0: 	}
samer@0: 
samer@0: 	public static void pingBasis(Matrix A) {
samer@0: 		pingBasis(A,Shell.getDouble("gamma",0.5));
samer@0: 	}
samer@0: 
samer@0: 	public static void pingBasis(Matrix A, double gamma)
samer@0: 	{
samer@0: 		int extra = (int)(3.0*16.0/gamma);
samer@0: 		int m=A.getColumnDimension();
samer@0: 		int n=A.getRowDimension();
samer@0: 		double [][] a = A.getArray();
samer@0: 
samer@0: 		A.zero();
samer@0: 
samer@0: 		for (int j=0; j<m; j++) {
samer@0: 			int jj=(int)((n+extra)*Math.random())-extra;
samer@0: 			double omega=0.2+2*Math.random();
samer@0: 			double t=0.0;
samer@0: 			for (int i=0; i<n; i++) {
samer@0: 				if (i>=jj) {
samer@0: 					t=i-jj;
samer@0: 					a[i][j]=Math.exp(-gamma*t/16)*Math.sin(omega*t);
samer@0: 				} else a[i][j]=0;
samer@0: 			}
samer@0: 		}
samer@0: 		A.changed();
samer@0: 	}
samer@0: 
samer@0: 	public static void fuzzyIdentity(Matrix matrix) {
samer@0: 		int		n = matrix.getRowDimension();
samer@0: 		int		m = matrix.getColumnDimension();
samer@0: 		fuzzyIdentity(matrix,Shell.getDouble("sigma",
samer@0: 			(n>m) ? n/(double)m : m/(double)n));
samer@0: 	}
samer@0: 
samer@0: 	public static void fuzzyIdentity(Matrix matrix, double s) 
samer@0: 	{
samer@0: 		int		n = matrix.getRowDimension();
samer@0: 		int		m = matrix.getColumnDimension();
samer@0: 		double	t = s/Math.max(n,m);
samer@0: 		double	I[][] = matrix.getArray();
samer@0: 
samer@0: 		for (int i=0; i<n; i++) {
samer@0: 			for (int j=0; j<m; j++) {
samer@0: 				double Z = j/(double)(m-1) - i/(double)(n-1);
samer@0: 				I[i][j] = Math.exp(-(Z*Z)/(2*t*t));
samer@0: 			}
samer@0: 		}
samer@0: 
samer@0: 		matrix.changed();
samer@0: 	}
samer@0: }
samer@0: