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/*=========================================================================
*
* 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.
*
*=========================================================================*/
#include "itkCompensatedSummation.h"
#include "itkStdStreamStateSave.h"
#include "itkMath.h"
#include "itkMersenneTwisterRandomVariateGenerator.h"
int itkCompensatedSummationTest( int, char * [] )
{
// Save the format stream variables for std::cout
// They will be restored when coutState goes out of scope
// scope.
itk::StdStreamStateSave coutState(std::cout);
typedef float FloatType;
long int seedValue = 17;
const FloatType expectedMean = 0.5;
const itk::SizeValueType accumSize = 50000000;
typedef itk::Statistics::MersenneTwisterRandomVariateGenerator GeneratorType;
GeneratorType::Pointer generator = GeneratorType::New();
generator->Initialize( seedValue );
FloatType vanillaSum = 0.0;
typedef itk::CompensatedSummation< FloatType > CompensatedSummationType;
CompensatedSummationType floatAccumulator;
FloatType randomNumber;
for( itk::SizeValueType ii = 0; ii < accumSize; ++ii )
{
randomNumber = generator->GetVariate();
vanillaSum += randomNumber;
floatAccumulator.AddElement( randomNumber );
}
const FloatType vanillaMean = vanillaSum / static_cast< FloatType >( accumSize );
const FloatType vanillaError = itk::Math::abs( vanillaMean - expectedMean );
const FloatType accumulatorSum = floatAccumulator.GetSum();
const FloatType accumulatorMean = accumulatorSum / static_cast< FloatType >( accumSize );
const FloatType accumulatorError = itk::Math::abs( accumulatorMean - expectedMean );
std::cout << "The expected mean is: " << expectedMean << std::endl;
std::cout << "The vanilla sum is: " << vanillaSum << std::endl;
std::cout << "The vanilla mean is: " << vanillaMean << std::endl;
std::cout << "The vanilla error is: " << vanillaError << std::endl;
std::cout << "The accumulator sum is: " << accumulatorSum << std::endl;
std::cout << "The accumulator mean is: " << accumulatorMean << std::endl;
std::cout << "The accumulator error is: " << accumulatorError << std::endl;
if( vanillaError <= accumulatorError || accumulatorError > 1.0e-4 )
{
std::cerr << "The compensated summation did not compensate well (crazy compiler flags?)." << std::endl;
return EXIT_FAILURE;
}
// exercise other methods
CompensatedSummationType floatAccumulatorCopy = floatAccumulator;
if( itk::Math::NotExactlyEquals(floatAccumulatorCopy.GetSum(), floatAccumulator.GetSum()) )
{
std::cerr << "The copy constructor failed." << std::endl;
return EXIT_FAILURE;
}
CompensatedSummationType floatAccumulatorCopy2;
floatAccumulatorCopy2 = floatAccumulator;
if( itk::Math::NotExactlyEquals(floatAccumulatorCopy2.GetSum(), floatAccumulator.GetSum()) )
{
std::cerr << "The assignment operator failed." << std::endl;
return EXIT_FAILURE;
}
floatAccumulator += randomNumber;
floatAccumulator -= randomNumber;
if( itk::Math::NotAlmostEquals( floatAccumulatorCopy2.GetSum(), floatAccumulator.GetSum() ) )
{
std::cerr << "The operator+= and operator-= are not reversible." << std::endl;
return EXIT_FAILURE;
}
floatAccumulator *= randomNumber;
floatAccumulator /= randomNumber;
if( itk::Math::NotAlmostEquals( floatAccumulatorCopy2.GetSum(), floatAccumulator.GetSum() ) )
{
std::cerr << "The operator*= and operator/= are not reversible." << std::endl;
return EXIT_FAILURE;
}
floatAccumulator.ResetToZero();
if( itk::Math::NotAlmostEquals( floatAccumulator.GetSum(), itk::NumericTraits< FloatType >::ZeroValue() ) )
{
std::cerr << "GetSize() did return the correct value!" << std::endl;
return EXIT_FAILURE;
}
floatAccumulator = 2.0;
if( floatAccumulator.GetSum() != 2.0 )
{
std::cerr << "operator= did not set the value." << std::endl;
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
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