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/*=========================================================================
*
* Copyright NumFOCUS
*
* 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
*
* https://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.
*
*=========================================================================*/
#ifndef itkQuaternionRigidTransformGradientDescentOptimizer_h
#define itkQuaternionRigidTransformGradientDescentOptimizer_h
#include "itkGradientDescentOptimizer.h"
#include "ITKOptimizersExport.h"
namespace itk
{
/** \class QuaternionRigidTransformGradientDescentOptimizer
* \brief Implement a gradient descent optimizer
*
* QuaternionRigidTransformGradientDescentOptimizer is an extension to the
* simple gradient descent optimizer implemented in GradientDescentOptimizer.
* At each iteration the current position is updated according to
*
* p(n+1) = p(n) + learningRate * d f(p(n)) / d p(n)
*
* \f[
* p_{n+1} = p_n
* + \mbox{learningRate}
* \, \frac{\partial f(p_n) }{\partial p_n}
* \f]
*
* The learning rate is a fixed scalar defined via SetLearningRate().
* The optimizer steps through a user defined number of iterations;
* no convergence checking is done.
* The first four components of p are assumed to be the four components
* of the quaternion. After each update, the quaternion is normalized to
* have a magnitude of one. This ensures the transform is purely rigid.
*
* \sa GradientDescentOptimizer
* \ingroup Numerics Optimizers
* \ingroup ITKOptimizers
*/
class ITKOptimizers_EXPORT QuaternionRigidTransformGradientDescentOptimizer : public GradientDescentOptimizer
{
public:
ITK_DISALLOW_COPY_AND_MOVE(QuaternionRigidTransformGradientDescentOptimizer);
/** Standard class type aliases. */
using Self = QuaternionRigidTransformGradientDescentOptimizer;
using Superclass = GradientDescentOptimizer;
using Pointer = SmartPointer<Self>;
using ConstPointer = SmartPointer<const Self>;
/** Method for creation through the object factory. */
itkNewMacro(Self);
/** \see LightObject::GetNameOfClass() */
itkOverrideGetNameOfClassMacro(QuaternionRigidTransformGradientDescentOptimizer);
/** Parameters type.
* It defines a position in the optimization search space. */
using ParametersType = Superclass::ParametersType;
/** Advance one step following the gradient direction. */
void
AdvanceOneStep() override;
protected:
QuaternionRigidTransformGradientDescentOptimizer() = default;
~QuaternionRigidTransformGradientDescentOptimizer() override = default;
};
} // end namespace itk
#endif
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