1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
/*=========================================================================
*
* 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.
*
*=========================================================================*/
#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);
using FloatType = float;
long seedValue = 17;
constexpr FloatType expectedMean = 0.5;
constexpr itk::SizeValueType accumSize = 50000000;
using GeneratorType = itk::Statistics::MersenneTwisterRandomVariateGenerator;
auto generator = GeneratorType::New();
generator->Initialize(seedValue);
FloatType vanillaSum = 0.0;
using CompensatedSummationType = itk::CompensatedSummation<FloatType>;
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(), FloatType{}))
{
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;
}
|
