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/*=========================================================================
Program: Insight Segmentation & Registration Toolkit
Module: $RCSfile: itkPowellOptimizerTest.cxx,v $
Language: C++
Date: $Date: 2005-02-08 03:18:41 $
Version: $Revision: 1.3 $
Copyright (c) Insight Software Consortium. All rights reserved.
See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notices for more information.
=========================================================================*/
#if defined(_MSC_VER)
#pragma warning ( disable : 4786 )
#endif
#include <itkPowellOptimizer.h>
#include <vnl/vnl_math.h>
int POWELL_CALLS_TO_GET_VALUE = 0;
/**
* The objectif function is the quadratic form:
*
* 1/2 x^T A x - b^T x
*
* Where A is a matrix and b is a vector
* The system in this example is:
*
* | 3 2 ||x| | 2| |0|
* | 2 6 ||y| + |-8| = |0|
*
*
* the solution is the vector | 2 -2 |
*
*/
class PowellBoundedCostFunction : public itk::SingleValuedCostFunction
{
public:
typedef PowellBoundedCostFunction Self;
typedef itk::SingleValuedCostFunction Superclass;
typedef itk::SmartPointer<Self> Pointer;
typedef itk::SmartPointer<const Self> ConstPointer;
itkNewMacro( Self );
itkTypeMacro( PowellBoundedCostFunction, SingleValuedCostFunction );
enum { SpaceDimension=2 };
typedef Superclass::ParametersType ParametersType;
typedef Superclass::DerivativeType DerivativeType;
typedef Superclass::MeasureType MeasureType ;
PowellBoundedCostFunction()
{
}
void GetDerivative( const ParametersType & ,
DerivativeType & ) const
{
}
MeasureType GetValue( const ParametersType & parameters ) const
{
++POWELL_CALLS_TO_GET_VALUE;
double x = parameters[0];
double y = parameters[1];
std::cout << " GetValue( " ;
std::cout << x << " ";
std::cout << y << ") = ";
MeasureType measure = 0.5*(3*x*x+4*x*y+6*y*y) - 2*x + 8*y;
std::cout << measure << std::endl;
return measure;
}
unsigned int GetNumberOfParameters(void) const
{
return SpaceDimension;
}
private:
};
int itkPowellOptimizerTest(int, char* [] )
{
std::cout << "Powell Optimizer Test ";
std::cout << std::endl << std::endl;
typedef itk::PowellOptimizer OptimizerType;
typedef OptimizerType::ScalesType ScalesType;
// Declaration of a itkOptimizer
OptimizerType::Pointer itkOptimizer = OptimizerType::New();
// Declaration of the CostFunction
PowellBoundedCostFunction::Pointer costFunction = PowellBoundedCostFunction::New();
itkOptimizer->SetCostFunction( costFunction.GetPointer() );
typedef PowellBoundedCostFunction::ParametersType ParametersType;
const unsigned int spaceDimension =
costFunction->GetNumberOfParameters();
// We start not so far from | 2 -2 |
ParametersType initialPosition( spaceDimension );
initialPosition[0] = 100;
initialPosition[1] = -100;
itkOptimizer->SetMaximize(false);
itkOptimizer->SetStepLength( 10 );
itkOptimizer->SetStepTolerance( 0.1 );
itkOptimizer->SetValueTolerance( 0.1 );
itkOptimizer->SetMaximumIteration( 100 );
itkOptimizer->SetInitialPosition( initialPosition );
try
{
itkOptimizer->StartOptimization();
}
catch( itk::ExceptionObject & e )
{
std::cout << "Exception thrown ! " << std::endl;
std::cout << "An error ocurred during Optimization" << std::endl;
std::cout << "Location = " << e.GetLocation() << std::endl;
std::cout << "Description = " << e.GetDescription() << std::endl;
return EXIT_FAILURE;
}
ParametersType finalPosition = itkOptimizer->GetCurrentPosition();
std::cout << "Solution = (";
std::cout << finalPosition[0] << "," ;
std::cout << finalPosition[1] << ")" << std::endl;
//
// check results to see if it is within range
//
bool pass = true;
double trueParameters[2] = { 2, -2 };
for( unsigned int j = 0; j < 2; j++ )
{
if( vnl_math_abs( finalPosition[j] - trueParameters[j] ) > 0.01 )
pass = false;
}
// Exercise various member functions.
std::cout << "Maximize: " << itkOptimizer->GetMaximize() << std::endl;
std::cout << "StepLength: " << itkOptimizer->GetStepLength();
std::cout << std::endl;
std::cout << "CurrentIteration: " << itkOptimizer->GetCurrentIteration();
std::cout << std::endl;
itkOptimizer->Print( std::cout );
std::cout << "Calls to GetValue = " << POWELL_CALLS_TO_GET_VALUE << std::endl;
if( !pass )
{
std::cout << "Test failed." << std::endl;
return EXIT_FAILURE;
}
std::cout << "Test passed." << std::endl;
return EXIT_SUCCESS;
}
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