text: /*=========================================================================
   *
   *  Copyright Insight Software Consortium
   *
   *  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.
   *
   *=========================================================================*/
  #ifndef itkStandardDeviationPerComponentSampleFilter_h
  #define itkStandardDeviationPerComponentSampleFilter_h
  
  #include "itkProcessObject.h"
  
  #include "itkVariableSizeMatrix.h"
  #include "itkSimpleDataObjectDecorator.h"
  #include "itkNumericTraitsFixedArrayPixel.h"
  
  namespace itk
  {
  namespace Statistics
  {
  /** \class StandardDeviationPerComponentSampleFilter
   * \brief Calculates the covariance matrix of the target sample data.
   *
   * The filter calculates first the sample mean and use it in the covariance
   * calculation. The covariance is computed as follows
   * Let \f$\Sigma\f$ denotes covariance matrix for the sample, then:
   * When \f$x_{i}\f$ is \f$i\f$th component of a measurement vector
   * \f$\vec x\f$, \f$\mu_{i}\f$ is the \f$i\f$th component of the \f$\vec\mu\f$,
   * and the \f$\sigma_{ij}\f$ is the \f$ij\f$th component \f$\Sigma\f$,
   * \f$\sigma_{ij} = (x_{i} - \mu_{i})(x_{j} - \mu_{j})\f$
   *
   * Without the plugged in mean vector, this calculator will perform
   * the single pass mean and covariance calculation algorithm.
   *
   * \ingroup ITKStatistics
   */
  
  template <typename TSample>
  class ITK_TEMPLATE_EXPORT StandardDeviationPerComponentSampleFilter : public ProcessObject
  {
  public:
    ITK_DISALLOW_COPY_AND_ASSIGN(StandardDeviationPerComponentSampleFilter);
  
    /** Standard class type aliases. */
    using Self = StandardDeviationPerComponentSampleFilter;
    using Superclass = ProcessObject;
    using Pointer = SmartPointer<Self>;
    using ConstPointer = SmartPointer<const Self>;
    using SampleType = TSample;
  
    /** Standard Macros */
    itkTypeMacro(StandardDeviationPerComponentSampleFilter, ProcessObject);
    itkNewMacro(Self);
  
    /** Length of a measurement vector */
    using MeasurementVectorSizeType = typename TSample::MeasurementVectorSizeType;
  
    /** Measurement vector type */
    using MeasurementVectorType = typename TSample::MeasurementVectorType;
    using MeasurementVectorRealType = typename NumericTraits<MeasurementVectorType>::RealType;
  
    /** Method to set/get the sample */
    using Superclass::SetInput;
    void
    SetInput(const SampleType * sample);
  
    const SampleType *
    GetInput() const;
  
    /** MeasurementVector is not a DataObject, we need to decorate it to push it down
     * a ProcessObject's pipeline */
    using MeasurementVectorRealDecoratedType = SimpleDataObjectDecorator<MeasurementVectorRealType>;
  
    using OutputType = MeasurementVectorRealDecoratedType;
  
    /** Return the standard deviation vector */
    const MeasurementVectorRealType
    GetStandardDeviationPerComponent() const;
  
    const MeasurementVectorRealDecoratedType *
    GetStandardDeviationPerComponentOutput() const;
  
    /** Return the mean vector */
    const MeasurementVectorRealType
    GetMeanPerComponent() const;
  
    const MeasurementVectorRealDecoratedType *
    GetMeanPerComponentOutput() const;
  
  protected:
    StandardDeviationPerComponentSampleFilter();
    ~StandardDeviationPerComponentSampleFilter() override = default;
    void
    PrintSelf(std::ostream & os, Indent indent) const override;
  
    /** DataObject pointer */
    using DataObjectPointer = DataObject::Pointer;
  
    using DataObjectPointerArraySizeType = ProcessObject::DataObjectPointerArraySizeType;
    using Superclass::MakeOutput;
    DataObjectPointer
    MakeOutput(DataObjectPointerArraySizeType idx) override;
  
    void
    GenerateData() override;
  
    MeasurementVectorSizeType
    GetMeasurementVectorSize() const;
  
  private:
  }; // end of class
  } // end of namespace Statistics
  } // end of namespace itk
  
  #ifndef ITK_MANUAL_INSTANTIATION
  #  include "itkStandardDeviationPerComponentSampleFilter.hxx"
  #endif
  
  #endif
  