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/*=========================================================================
*
* Copyright UMC Utrecht and contributors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*=========================================================================*/
#include "itkLineSearchOptimizer.h"
#include "itkNumericTraits.h"
namespace itk
{
/**
* ******************* Constructor *******************
*/
LineSearchOptimizer::LineSearchOptimizer()
{
this->m_CurrentStepLength = 0.0;
this->m_MinimumStepLength = 0.0;
this->m_MaximumStepLength = NumericTraits<double>::max();
this->m_InitialStepLengthEstimate = 1.0;
} // end Constructor
/**
* ***************** SetCurrentStepLength *************
*
* Set the current step length AND the current position, where
* the current position is computed as:
* m_CurrentPosition =
* m_InitialPosition + StepLength * m_LineSearchDirection
*/
void
LineSearchOptimizer::SetCurrentStepLength(double step)
{
itkDebugMacro("Setting current step length to " << step);
this->m_CurrentStepLength = step;
ParametersType newPosition = this->GetInitialPosition();
const unsigned int numberOfParameters = newPosition.GetSize();
const ParametersType & LSD = this->GetLineSearchDirection();
for (unsigned int i = 0; i < numberOfParameters; ++i)
{
newPosition[i] += (step * LSD[i]);
}
this->SetCurrentPosition(newPosition);
} // end SetCurrentStepLength()
/**
* ******************** DirectionalDerivative **************************
*
* Computes the inner product of the argument and the line search direction
*/
double
LineSearchOptimizer::DirectionalDerivative(const DerivativeType & derivative) const
{
/** Easy, thanks to the functions defined in vnl_vector.h */
return inner_product(derivative, this->GetLineSearchDirection());
} // end DirectionalDerivative()
/**
* ******************** PrintSelf **************************
*/
void
LineSearchOptimizer::PrintSelf(std::ostream & os, Indent indent) const
{
/** Call the superclass' PrintSelf. */
Superclass::PrintSelf(os, indent);
os << indent << "CurrentStepLength: " << this->m_CurrentStepLength << std::endl;
os << indent << "MinimumStepLength: " << this->m_MinimumStepLength << std::endl;
os << indent << "MaximumStepLength: " << this->m_MaximumStepLength << std::endl;
os << indent << "InitialStepLengthEstimate: " << this->m_InitialStepLengthEstimate << std::endl;
os << indent << "LineSearchDirection: " << this->m_LineSearchDirection << std::endl;
} // end PrintSelf()
} // end namespace itk
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