//
//  MathLib.java
//  Stella2Java
//
//  Created by djoiner on Thu Dec 20 2001.
//  Copyright (c) 2001 __MyCompanyName__. All rights reserved.
//

public class MathLib {

    public static double niceNumber ( double x, boolean round) {
        int exp;
        double frac;
        double niceFrac;
        
        exp = (int)Math.floor(log10(x));
        frac = x/Math.pow(10.0,exp);
        if (round) {
            if (frac < 1.5) {
                niceFrac=1.0;
            } else if (frac<3.0) {
                niceFrac=2.0;
            } else if (frac<7.0) {
                niceFrac=5.0;
            } else {
                niceFrac=10.0;
            }
        } else {
            if (frac <= 1.0001) {
                niceFrac=1.0;
            } else if (frac<=2.0001) {
                niceFrac=2.0;
            } else if (frac<=5.0001) {
                niceFrac=5.0;
            } else {
                niceFrac=10.0;
            }
        }
        return niceFrac * Math.pow(10.0,exp);
    }
    
    public static final double log10Constant = Math.log(10.0);
    
    public static double log10(double x) {
        return Math.log(x)/log10Constant;
    }
    
    public static double [] niceLabels (int nLabel, double minLabel, double maxLabel) {
        double [] label = new double[nLabel];
        int nfrac;
        double d;
        double graphmin, graphmax;
        double range, x;
        
        range = niceNumber(maxLabel-minLabel, true);
        d = niceNumber(range/(nLabel-1),true);
        graphmin = Math.floor(minLabel/d)*d;
        graphmax = Math.ceil(maxLabel/d)*d;
        nfrac = Math.max((int)log10(d),0);
        
        for (int i=0; i<nLabel; i++) {
            x = graphmin + (double)i*d;
            label[i] = x;
        }
        
        return label;
    }

    public static double [] niceLogLabels(int nLabel, double minLabel, double maxLabel) {
        double minLogLabel = log10(minLabel);
        double maxLogLabel = log10(maxLabel);
        double [] niceLogLabel = MathLib.niceLabels(nLabel,minLogLabel,maxLogLabel);
        for (int i=0;i<nLabel;i++) {
            niceLogLabel[i] = MathLib.niceNumber(
                Math.pow(10.0,niceLogLabel[i]),false);
        }
        return niceLogLabel;
    }

    public static double cartesianToR(double x, double y, double z) {
        return Math.sqrt(x*x+y*y+z*z);
    }
    public static double cartesianToPhi(double r, double z) {
        if (r>0.0) {
            return Math.acos(z/r);
        } else {
            return 0.0;
        }
    }
    public static double cartesianToPhi(double x, double y, double z) {
        return cartesianToPhi(cartesianToR(x,y,z),z);
    }
    public static double cartesianToTheta(double x, double y) {
        double pi = Math.PI;
        double retval;
        if (x==0.0&&y==0.0) {
            return 0.0;
        } else if (x == 0.0) {
            if (y>=0.0) return pi/2.0;
            else return -pi/2.0;
        } else if (y==0.0) {
            if (x>=0.0) return 0.0;
            else return pi;
        } else {
            if (x>=0.0) retval=Math.atan(y/x);
            else retval=Math.atan(y/x)+pi;
        }
        if(retval<0.0) retval+=2.0*pi;
        return retval;
    }

    public static double [] linearGrid(int n, double min, double max) {
        
        double diff = (max-min)/(double)(n-1);
        double [] retval = new double[n];
        
        retval[0] = min;
        retval[n-1]=max;
        for(int i=1;i<n-1;i++) {
            retval[i]=retval[0]+diff*i;
        }
        
        return retval;
    }
    
    public static int factorial (int n) {
        int retval=1;
        for (int i=2;i<=n;i++) {
            retval*=i;
        }
        return retval;
    }
    public static int doubleFactorial(int l) {
        int i;
        int retval=1;
        for (i=l;i>=2;i-=2) retval*=i;
        return retval;
    }

}