text: /*=========================================================================
   *
   *  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
   *
   *         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 "itkAtan2ImageFilter.h"
  #include "itkImageRegionIteratorWithIndex.h"
  #include "itkMath.h"
  #include "itkTestingMacros.h"
  
  
  int
  itkAtan2ImageFilterTest(int, char *[])
  {
  
    // Define the dimension of the images
    constexpr unsigned int ImageDimension = 3;
  
    // Declare the pixel types of the images
    using PixelType = float;
  
    // Declare the types of the images
    using InputImageType = itk::Image<PixelType, ImageDimension>;
    using OutputImageType = itk::Image<PixelType, ImageDimension>;
  
    // Declare appropriate Iterator types for each image
    using InputIteratorType = itk::ImageRegionIteratorWithIndex<InputImageType>;
  
    using OutputIteratorType = itk::ImageRegionIteratorWithIndex<OutputImageType>;
  
    // Declare the type of the index to access images
    using IndexType = itk::Index<ImageDimension>;
  
    // Declare the type of the size
    using SizeType = itk::Size<ImageDimension>;
  
    // Declare the type of the Region
    using RegionType = itk::ImageRegion<ImageDimension>;
  
    // Create two images
    InputImageType::Pointer sinImage = InputImageType::New();
    InputImageType::Pointer cosImage = InputImageType::New();
  
    // Define their size, and start index
    SizeType size;
    size[0] = 2;
    size[1] = 2;
    size[2] = 2;
  
    IndexType start;
    start[0] = 0;
    start[1] = 0;
    start[2] = 0;
  
    RegionType region;
    region.SetIndex(start);
    region.SetSize(size);
  
    // Initialize Sinus Image
    sinImage->SetRegions(region);
    sinImage->Allocate();
  
    // Initialize Cosinus Image
    cosImage->SetRegions(region);
    cosImage->Allocate();
  
    // Create one iterator for the Input Image (this is a light object)
    InputIteratorType it1(sinImage, sinImage->GetBufferedRegion());
  
    // Initialize the content of Image A
    const double sinValue = std::sin(itk::Math::pi / 6.0);
    it1.GoToBegin();
    while (!it1.IsAtEnd())
    {
      it1.Set(sinValue);
      ++it1;
    }
  
    // Create one iterator for the Input Image (this is a light object)
    InputIteratorType it2(cosImage, cosImage->GetBufferedRegion());
  
    // Initialize the content of Image A
    const double cosValue = std::cos(itk::Math::pi / 6.0);
    it2.GoToBegin();
    while (!it2.IsAtEnd())
    {
      it2.Set(cosValue);
      ++it2;
    }
  
    // Declare the type for the Atan filter
    using FilterType = itk::Atan2ImageFilter<InputImageType, InputImageType, OutputImageType>;
  
    // Create the Filter
    FilterType::Pointer filter = FilterType::New();
  
    ITK_EXERCISE_BASIC_OBJECT_METHODS(filter, Atan2ImageFilter, BinaryGeneratorImageFilter);
  
    // Set the input images
    filter->SetInput1(sinImage);
    filter->SetInput2(cosImage);
  
    // Get the filter output
    OutputImageType::Pointer outputImage = filter->GetOutput();
  
    // Execute the filter
    filter->Update();
  
    // Create an iterator for going through the image output
    OutputIteratorType ot(outputImage, outputImage->GetRequestedRegion());
  
    // Check the content of the result image
    const OutputImageType::PixelType epsilon = 1e-6;
    ot.GoToBegin();
  
    it1.GoToBegin();
    it2.GoToBegin();
  
    while (!ot.IsAtEnd())
    {
      const InputImageType::PixelType  input1 = it1.Get();
      const InputImageType::PixelType  input2 = it2.Get();
      const OutputImageType::PixelType output = ot.Get();
      const OutputImageType::PixelType atan2 = std::atan2(input1, input2);
      if (!itk::Math::FloatAlmostEqual(atan2, output, 10, epsilon))
      {
        std::cerr.precision(static_cast<int>(itk::Math::abs(std::log10(epsilon))));
        std::cerr << "Error " << std::endl;
        std::cerr << " std::atan2( " << input1 << ", " << input2 << ") = " << atan2 << std::endl;
        std::cerr << " differs from " << output;
        std::cerr << " by more than " << epsilon << std::endl;
        return EXIT_FAILURE;
      }
      ++ot;
      ++it1;
    }
  
    return EXIT_SUCCESS;
  }
  