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SqrtLowParameterTransformation.cxx
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1 // @(#)root/minuit2:$Id$
2 // Authors: M. Winkler, F. James, L. Moneta, A. Zsenei 2003-2005
3 
4 /**********************************************************************
5  * *
6  * Copyright (c) 2005 LCG ROOT Math team, CERN/PH-SFT *
7  * *
8  **********************************************************************/
9 
10 // Project : LCG
11 // Package : Minuit
12 // Author : Lorenzo.MONETA@cern.ch
13 // Created by: moneta at Thu Apr 8 10:26:22 2004
14 
17 
18 namespace ROOT {
19 
20 namespace Minuit2 {
21 
22 double SqrtLowParameterTransformation::Int2ext(double value, double lower) const
23 {
24  /// internal to external transformation
25  double val = lower - 1. + std::sqrt(value * value + 1.);
26  return val;
27 }
28 
29 double SqrtLowParameterTransformation::Ext2int(double value, double lower, const MnMachinePrecision &) const
30 {
31  // external to internal transformation
32  double yy = value - lower + 1.;
33  double yy2 = yy * yy;
34  if (yy2 < 1.)
35  return 0;
36  else
37  return std::sqrt(yy2 - 1);
38 }
39 
40 double SqrtLowParameterTransformation::DInt2Ext(double value, double) const
41 {
42  // derivative of internal to external transofrmation : d (Int2Ext) / d Int
43  double val = value / (std::sqrt(value * value + 1.));
44  return val;
45 }
46 
47 } // namespace Minuit2
48 
49 } // namespace ROOT
ROOT::Minuit2::SqrtLowParameterTransformation::DInt2Ext
double DInt2Ext(double Value, double Lower) const
Definition: SqrtLowParameterTransformation.cxx:40
MnMachinePrecision.h
ROOT::Minuit2::SqrtLowParameterTransformation::Ext2int
double Ext2int(double Value, double Lower, const MnMachinePrecision &) const
Definition: SqrtLowParameterTransformation.cxx:29
SqrtLowParameterTransformation.h
ROOT::Minuit2::MnMachinePrecision
Sets the relative floating point (double) arithmetic precision.
Definition: MnMachinePrecision.h:32
sqrt
double sqrt(double)
ROOT::Minuit2::SqrtLowParameterTransformation::Int2ext
double Int2ext(double Value, double Lower) const
Definition: SqrtLowParameterTransformation.cxx:22
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