/*
 * T.java
 *
 * Created on March 8, 2006, 1:06 PM
 *
 * To change this template, choose Tools | Options and locate the template under
 * the Source Creation and Management node. Right-click the template and choose
 * Open. You can then make changes to the template in the Source Editor.
 */

package probabilitycalculator;

/**
 *
 * @author Rinaman
 */
public class T extends Distributions {
    
    private double x;
    private int df, option;
    
    /** Creates a new instance of T */
    public T(double dx, int ParmOne, int ioption) {
        x = dx;
        df = ParmOne;
        option = ioption;
    }
    
    public double TCalc() {
        double xdf;
        xdf =  (double)df;
        if(option == 1) return df(x, xdf, 0.0);
        else if(option == 2) return 1.0 - df(x, xdf, 0.0);
        else if(option == 3) return invdfT(x, xdf, 0.0);
        else return invdfT(1.0 - x, xdf, 0.0);
    }
    
    public double invdfT(double x, double df, double parmtwo) {
        double lo, hi, dflo, dfhi;
        if(x <= 0.0)return -1.0e-12;
        if(x >= 1.0)return 1.0e12;
        if(x < 0.5) {
            lo = -100.0;
            hi = 0.0;
            dflo = x - df(lo, df, 0.0);
            dfhi = x - df(hi, df, 0.0);
            while(dflo*dfhi > 0.0) {
                hi = lo;
                lo = lo - 10.0;
            }
        }
        else {
            lo = 0.0;
            hi = 100.0;
            dflo = x - df(lo, df, 0.0);
            dfhi = x - df(hi, df, 0.0);
            while(dflo*dfhi > 0.0) {
                lo = hi;
                hi = hi + 10.0;
                dflo = x - df(lo, df, 0.0);
                dfhi = x - df(hi, df, 0.0);
            }  
        }
        return rtflsp(x, lo, hi, 1.0e-6,  df, 0.0);
    }
            
    public double df(double x, double df, double parmtwo) {
        double intt;
        if(x == 0.0)return 0.5;
        intt = 1.0 - betai(df/2.0, 0.5, df/(df+x*x));
        if(x > 0.0)return intt + (1.0-intt)/2.0;
        else return (1.0 - intt)/2.0; 
    }
}