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GSLMinimizer1D.cxx
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1 // @(#)root/mathmore:$Id$
2 // Authors: L. Moneta, A. Zsenei 08/2005
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23 
24 // Implementation file for class GSLMinimizer1D
25 //
26 // Created by: moneta at Wed Dec 1 15:04:51 2004
27 //
28 // Last update: Wed Dec 1 15:04:51 2004
29 //
30 
31 #include <assert.h>
32 
33 #include "Math/GSLMinimizer1D.h"
34 #include "Math/Error.h"
35 
36 #include "GSLFunctionWrapper.h"
37 #include "GSL1DMinimizerWrapper.h"
38 
39 
40 #include "gsl/gsl_min.h"
41 #include "gsl/gsl_errno.h"
42 
43 #include <iostream>
44 #include <cmath>
45 
46 namespace ROOT {
47 
48 namespace Math {
49 
50 
52  fXmin(0), fXlow(0), fXup(0), fMin(0), fLow(0), fUp(0),
53  fIter(0), fStatus(-1), fIsSet(false),
54  fMinimizer(0), fFunction(0)
55 {
56  // construct a minimizer passing the algorithm type as an enumeration
57 
58  const gsl_min_fminimizer_type* T = 0 ;
59  switch ( type )
60  {
62  T = gsl_min_fminimizer_goldensection;
63  break ;
64  case Minim1D::kBRENT :
65  T = gsl_min_fminimizer_brent;
66  break ;
67  default :
68  // default case is brent
69  T = gsl_min_fminimizer_brent;
70  break ;
71  }
72 
75 
76 }
77 
79 {
80  // destructor: clean up minimizer and function pointers
81 
82  if (fMinimizer) delete fMinimizer;
83  if (fFunction) delete fFunction;
84 }
85 
87 {
88  // dummy copy ctr
89 }
90 
92 {
93  // dummy operator =
94  if (this == &rhs) return *this; // time saving self-test
95  return *this;
96 }
97 
98 void GSLMinimizer1D::SetFunction( GSLFuncPointer f, void * p, double xmin, double xlow, double xup) {
99  // set the function to be minimized
100  assert(fFunction);
101  assert(fMinimizer);
102  fXlow = xlow;
103  fXup = xup;
104  fXmin = xmin;
106  fFunction->SetParams( p );
107 
108 #ifdef DEBUG
109  std::cout << " [ "<< xlow << " , " << xup << " ]" << std::endl;
110 #endif
111 
112  int status = gsl_min_fminimizer_set( fMinimizer->Get(), fFunction->GetFunc(), xmin, xlow, xup);
113  if (status != GSL_SUCCESS)
114  std::cerr <<"GSLMinimizer1D: Error: Interval [ "<< xlow << " , " << xup << " ] does not contain a minimum" << std::endl;
115 
116 
117  fIsSet = true;
118  fStatus = -1;
119  return;
120 }
121 
123  // perform an iteration and update values
124  if (!fIsSet) {
125  std::cerr << "GSLMinimizer1D- Error: Function has not been set in Minimizer" << std::endl;
126  return -1;
127  }
128 
129  int status = gsl_min_fminimizer_iterate(fMinimizer->Get());
130  // update values
131  fXmin = gsl_min_fminimizer_x_minimum(fMinimizer->Get() );
132  fMin = gsl_min_fminimizer_f_minimum(fMinimizer->Get() );
133  // update interval values
134  fXlow = gsl_min_fminimizer_x_lower(fMinimizer->Get() );
135  fXup = gsl_min_fminimizer_x_upper(fMinimizer->Get() );
136  fLow = gsl_min_fminimizer_f_lower(fMinimizer->Get() );
137  fUp = gsl_min_fminimizer_f_upper(fMinimizer->Get() );
138  return status;
139 }
140 
141 double GSLMinimizer1D::XMinimum() const {
142  // return x value at function minimum
143  return fXmin;
144 }
145 
146 double GSLMinimizer1D::XLower() const {
147  // return lower x value of bracketing interval
148  return fXlow;
149 }
150 
151 double GSLMinimizer1D::XUpper() const {
152  // return upper x value of bracketing interval
153  return fXup;
154 }
155 
157  // return function value at minimum
158  return fMin;
159 }
160 
162  // return function value at x lower
163  return fLow;
164 }
165 
167  // return function value at x upper
168  return fUp;
169 }
170 
171 const char * GSLMinimizer1D::Name() const {
172  // return name of minimization algorithm
173  return gsl_min_fminimizer_name(fMinimizer->Get() );
174 }
175 
176 bool GSLMinimizer1D::Minimize (int maxIter, double absTol, double relTol)
177 {
178  // find the minimum via multiple iterations
179  fStatus = -1;
180  int iter = 0;
181  int status = 0;
182  do {
183  iter++;
184  status = Iterate();
185  if (status != GSL_SUCCESS) {
186  MATH_ERROR_MSG("GSLMinimizer1D::Minimize","error returned when performing an iteration");
187  fStatus = status;
188  return false;
189  }
190 
191 #ifdef DEBUG
192  std::cout << "Min1D - iteration " << iter << " interval : [ " << fXlow << " , " << fXup << " ] min = " << fXmin
193  << " fmin " << fMin << " f(a) " << fLow << " f(b) " << fUp << std::endl;
194 #endif
195 
196 
197  status = TestInterval(fXlow, fXup, absTol, relTol);
198  if (status == GSL_SUCCESS) {
199  fIter = iter;
200  fStatus = status;
201  return true;
202  }
203  }
204  while (status == GSL_CONTINUE && iter < maxIter);
205  if (status == GSL_CONTINUE) {
206  double tol = std::abs(fXup-fXlow);
207  MATH_INFO_MSGVAL("GSLMinimizer1D::Minimize","exceeded max iterations, reached tolerance is not sufficient",tol);
208  }
209  fStatus = status;
210  return false;
211 }
212 
213 
214 int GSLMinimizer1D::TestInterval( double xlow, double xup, double epsAbs, double epsRel) {
215 // static function to test interval
216  return gsl_min_test_interval(xlow, xup, epsAbs, epsRel);
217 }
218 
219 } // end namespace Math
220 
221 } // end namespace ROOT
222 
GSLMinimizer1D & operator=(const GSLMinimizer1D &)
float xmin
Definition: THbookFile.cxx:93
GSLMinimizer1D(Minim1D::Type type=Minim1D::kBRENT)
Construct the minimizer passing the minimizer type using the Minim1D::Algorithm enumeration.
const double absTol
This namespace contains pre-defined functions to be used in conjuction with TExecutor::Map and TExecu...
Definition: StringConv.hxx:21
double T(double x)
Definition: ChebyshevPol.h:34
bool Minimize(int maxIter, double absTol, double relTol)
Find minimum position iterating until convergence specified by the absolute and relative tolerance or...
GSL1DMinimizerWrapper * fMinimizer
virtual ~GSLMinimizer1D()
Destructor: free allocated resources.
#define MATH_ERROR_MSG(loc, str)
Definition: Error.h:50
double(* GSLFuncPointer)(double, void *)
Function pointer corresponding to gsl_function signature.
const double tol
double XLower() const
Return current lower bound of the minimization interval.
double XUpper() const
Return current upper bound of the minimization interval.
static int TestInterval(double xlow, double xup, double epsAbs, double epsRel)
Test convergence of the interval.
int Iterate()
Perform a minimizer iteration and if an unexepcted problem occurr then an error code will be returned...
Minimizer for arbitrary one dimensional functions.
double f(double x)
int type
Definition: TGX11.cxx:120
double FValLower() const
Return function value at current lower bound of the minimization interval.
const char * Name() const
Return name of minimization algorithm.
void SetFuncPointer(GSLFuncPointer f)
set in the GSL C struct the pointer to the function evaluation
gsl_min_fminimizer * Get() const
Interface class for numerical methods for one-dimensional minimization.
Definition: IMinimizer1D.h:50
Namespace for new Math classes and functions.
Wrapper class to the gsl_function C structure.
double FValMinimum() const
Return function value at current estimate of the minimum.
double FValUpper() const
Return function value at current upper bound of the minimization interval.
Type
Enumeration with One Dimensional Minimizer Algorithms.
GSLFunctionWrapper * fFunction
void SetParams(void *p)
set in the GSL C struct the extra-object pointer
wrapper class for gsl_min_fminimizer structure
void SetFunction(const UserFunc &f, double xmin, double xlow, double xup)
Set, or reset, minimizer to use the function f and the initial search interval [xlow, xup], with a guess for the location of the minimum xmin.
#define MATH_INFO_MSGVAL(loc, str, x)
Definition: Error.h:65
double XMinimum() const
Return current estimate of the position of the minimum.