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: 
samer@0: import samer.core.*;
samer@0: import samer.maths.*;
samer@0: import samer.tools.*;
samer@0: import samer.functions.*;
samer@0: 
samer@0: /**
samer@0: 	Inverts a given FFT using an alternative magnitude spectrum
samer@0:   */
samer@0: 
samer@0: public class RescaledIFT extends FFT implements Task
samer@0: {
samer@0: 	Vec			mag;
samer@0: 	FFT			ft;
samer@0: 	double	k[];
samer@0: 	VVector out;
samer@0: 
samer@0: 	public RescaledIFT(FFT ft, Vec mag) throws Exception
samer@0: 	{
samer@0: 		super(ft.size());
samer@0: 		this.ft=ft;
samer@0: 		this.mag=mag;
samer@0: 		k=new double[N];
samer@0: 		invert();
samer@0: 		out=new VVector("ift.output", real);
samer@0: 	}
samer@0: 
samer@0: 	public VVector output() { return out; }
samer@0: 	
samer@0: 	public void dispose() {}
samer@0: 	public void starting() {}
samer@0: 	public void stopping() {}
samer@0: 	public void run() {
samer@0: 		Vec.Iterator mit=mag.iterator();
samer@0: 		int 		i, j;
samer@0: 
samer@0: 		for (i=0, j=N-1; mit.more(); i++, j--)
samer@0: 			k[j]=k[i]=mit.next()/abs(ft.real[i],ft.imag[i]);
samer@0: 		for (; i<=N/2; i++, j--) k[i]=k[j]=0;
samer@0: 
samer@0: 		for (i=0; i<N; i++) {
samer@0: 			j=bitrev[i];
samer@0: 			real[j]  = k[i]*ft.real[i];
samer@0: 			imag[j] = k[i]*ft.imag[i];
samer@0: 		}
samer@0: 		calculate();
samer@0: 		out.changed();
samer@0: 	}
samer@0: 
samer@0: 	private static double abs(double x,double y) { return Math.sqrt(x*x+y*y); }
samer@0: }
samer@0: