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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 itkFourierSeriesPath_hxx
#define itkFourierSeriesPath_hxx
#include <cmath>
namespace itk
{
template <unsigned int VDimension>
auto
FourierSeriesPath<VDimension>::Evaluate(const InputType & input) const -> OutputType
{
InputType theta;
OutputType output;
int numHarmonics;
numHarmonics = m_CosCoefficients->Size();
output.Fill(0);
const double PI = 4.0 * std::atan(1.0);
if (numHarmonics > 0)
{
output += m_CosCoefficients->ElementAt(0);
}
for (int n = 1; n < numHarmonics; ++n)
{
// input defined over [0,1] maps to theta defined over [0,2pi * n]
theta = PI * 2.0 * n * input;
output +=
(m_CosCoefficients->ElementAt(n) * std::cos(theta) + m_SinCoefficients->ElementAt(n) * std::sin(theta)) * 2.0;
}
return output;
}
template <unsigned int VDimension>
auto
FourierSeriesPath<VDimension>::EvaluateDerivative(const InputType & input) const -> VectorType
{
InputType theta;
VectorType output;
int numHarmonics;
numHarmonics = m_CosCoefficients->Size();
output.Fill(0);
const double PI = 4.0 * std::atan(1.0);
for (int n = 1; n < numHarmonics; ++n)
{
// input defined over [0,1] maps to theta defined over [0,2pi * n]
theta = PI * 2.0 * n * input;
output += (m_SinCoefficients->ElementAt(n) * std::cos(theta) - m_CosCoefficients->ElementAt(n) * std::sin(theta)) *
(2.0 * n);
}
return output;
}
template <unsigned int VDimension>
void
FourierSeriesPath<VDimension>::AddHarmonic(const VectorType & CosCoefficients, const VectorType & SinCoefficients)
{
unsigned int numHarmonics = m_CosCoefficients->Size();
m_CosCoefficients->InsertElement(numHarmonics, CosCoefficients);
m_SinCoefficients->InsertElement(numHarmonics, SinCoefficients);
this->Modified();
}
template <unsigned int VDimension>
FourierSeriesPath<VDimension>::FourierSeriesPath()
{
this->SetDefaultInputStepSize(1.0 / 50.0);
m_CosCoefficients = CoefficientsType::New();
m_SinCoefficients = CoefficientsType::New();
}
template <unsigned int VDimension>
void
FourierSeriesPath<VDimension>::PrintSelf(std::ostream & os, Indent indent) const
{
Superclass::PrintSelf(os, indent);
itkPrintSelfObjectMacro(CosCoefficients);
itkPrintSelfObjectMacro(SinCoefficients);
}
} // namespace itk
#endif
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