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88 lines
2.9 KiB
88 lines
2.9 KiB
/* |
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This file is part of Magnum. |
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Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, |
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2020, 2021, 2022, 2023, 2024, 2025, 2026 |
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Vladimír Vondruš <mosra@centrum.cz> |
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Permission is hereby granted, free of charge, to any person obtaining a |
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copy of this software and associated documentation files (the "Software"), |
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to deal in the Software without restriction, including without limitation |
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the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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and/or sell copies of the Software, and to permit persons to whom the |
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Software is furnished to do so, subject to the following conditions: |
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The above copyright notice and this permission notice shall be included |
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in all copies or substantial portions of the Software. |
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
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FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER |
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DEALINGS IN THE SOFTWARE. |
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*/ |
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#include <numeric> /* std::accumulate() */ |
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#include <vector> |
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#include <Corrade/Containers/ArrayView.h> |
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#include "Magnum/Magnum.h" |
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#include "Magnum/Math/Algorithms/KahanSum.h" |
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#include "Magnum/Math/Algorithms/Svd.h" |
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#include "Magnum/Math/Packing.h" |
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using namespace Magnum; |
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using namespace Magnum::Math::Literals; |
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/* Make sure the name doesn't conflict with any other snippets to avoid linker |
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warnings, unlike with `int main()` there now has to be a declaration to |
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avoid -Wmisssing-prototypes */ |
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void mainMathAlgorithms(); |
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void mainMathAlgorithms() { |
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{ |
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/* [kahanSum] */ |
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std::vector<Float> data(100000000, 1.0f); |
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Float a = std::accumulate(data.begin(), data.end(), 0.0f); // 1.667e7f |
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Float b = Math::Algorithms::kahanSum(data.begin(), data.end()); // 1.000e8f |
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/* [kahanSum] */ |
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static_cast<void>(a); |
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static_cast<void>(b); |
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} |
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{ |
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/* [kahanSum-iterative] */ |
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Containers::ArrayView<UnsignedByte> pixels; |
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Float sum = 0.0f, c = 0.0f; |
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for(UnsignedByte pixel: pixels) { |
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Float value = Math::unpack<Float>(pixel); |
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sum = Math::Algorithms::kahanSum(&value, &value + 1, sum, &c); |
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} |
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/* [kahanSum-iterative] */ |
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} |
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{ |
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enum: std::size_t { cols = 3, rows = 4 }; |
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/* [svd] */ |
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Math::RectangularMatrix<cols, rows, Double> m; |
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auto svd = Math::Algorithms::svd(m); |
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Math::RectangularMatrix<cols, rows, Double> uPart = svd->first(); |
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Math::Vector<cols, Double> wDiagonal = svd->second(); |
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// Extend U |
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Math::Matrix<rows, Double> u{Math::ZeroInit}; |
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for(std::size_t i = 0; i != rows; ++i) |
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u[i] = uPart[i]; |
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// Diagonal W |
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Math::RectangularMatrix<cols, rows, Double> w = |
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Math::RectangularMatrix<cols, rows, Double>::fromDiagonal(wDiagonal); |
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// u*w*v.transposed() == m |
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/* [svd] */ |
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static_cast<void>(w); |
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} |
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}
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