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.maths.opt;
samer@0: 
samer@0: public class Util
samer@0: {
samer@0: 	public static double maxabs(double [] x)
samer@0: 	{
samer@0: 		double m=Math.abs(x[0]);
samer@0: 		for (int i=1; i<x.length; i++) {
samer@0: 			if (x[i]<-m)	 m=-x[i];
samer@0: 			else if (x[i]>m) m=x[i];
samer@0: 		}
samer@0: 		return m;
samer@0: 	}
samer@0: 
samer@0: 	// returns abs(x)	> tol ? x : tol*sgn(x)
samer@0: 	public static double unzero(double x, double tol) {
samer@0: 		if (x>tol) return x;
samer@0: 		else if (x<-tol) return x;
samer@0: 		else if (x>0) return tol;
samer@0: 		else return -tol;
samer@0: 	}
samer@0: 
samer@0: 	public static boolean between(double b, double u, double c)
samer@0: 	{
samer@0: 		if (b<c) return ((b<u) && (u<c));
samer@0: 		else     return ((c<u) && (u<b));
samer@0: 	}
samer@0: 
samer@0: 	public static double clip(double lower, double t, double upper)
samer@0: 	{
samer@0: 		if (t<=lower) return lower;
samer@0: 		else if (t>=upper) return upper;
samer@0: 		else return t;
samer@0: 	}
samer@0: 
samer@0: 	public static double cubici( double f1, double g1, double f2, double g2, double lambda)
samer@0: 	{
samer@0: 		double z=g2+g1-3*(f2-f1)/lambda;
samer@0: 		double w=z*z-g1*g2;
samer@0: 		w = (w>0) ? Math.sqrt(w) : 0;
samer@0: 		return lambda*((z+g1+w)/(g2+g1+2*z));
samer@0: 	}
samer@0: 
samer@0: 	public static int find( int i, int [] A, int n)
samer@0: 	{
samer@0: 		for (int j=0; j<n; j++) {
samer@0: 			if (A[j]==i) return j;
samer@0: 		}
samer@0: 		return -1;		
samer@0: 	}
samer@0: }