SinParameterTransformation.java

package org.freehep.math.minuit;

/**
 *
 * @version $Id: SinParameterTransformation.java 8584 2006-08-10 23:06:37Z duns $
 */
class SinParameterTransformation
{
   double int2ext(double value, double upper, double lower)
   {
      return lower + 0.5*(upper - lower)*(Math.sin(value) + 1.);
   }
   double ext2int(double value, double upper, double lower, MnMachinePrecision prec)
   {
      double piby2 = 2.*Math.atan(1.);
      double distnn = 8.*Math.sqrt(prec.eps2());
      double vlimhi = piby2 - distnn;
      double vlimlo = -piby2 + distnn;
      
      double yy = 2.*(value - lower)/(upper - lower) - 1.;
      double yy2 = yy*yy;
      if(yy2 > (1. - prec.eps2()))
      {
         if(yy < 0.)
         {
            return vlimlo;
         } 
         else
         {
            return vlimhi;
         }
         
      } 
      else
      {
         return Math.asin(yy);
      }
   }
   double dInt2Ext(double value, double upper, double lower)
   {
      return 0.5*Math.abs((upper - lower)*Math.cos(value));
   }
}