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enc_linalg_test.cc (2217B)

      1 // Copyright (c) the JPEG XL Project Authors. All rights reserved.
      2 //
      3 // Use of this source code is governed by a BSD-style
      4 // license that can be found in the LICENSE file.
      5 
      6 #include "lib/jxl/enc_linalg.h"
      7 
      8 #include "lib/jxl/base/random.h"
      9 #include "lib/jxl/testing.h"
     10 
     11 namespace jxl {
     12 namespace {
     13 
     14 Matrix2x2 Diagonal(const Vector2& d) { return {{{d[0], 0.0}, {0.0, d[1]}}}; }
     15 
     16 Matrix2x2 Identity() { return Diagonal({1.0, 1.0}); }
     17 
     18 Matrix2x2 MatMul(const Matrix2x2& A, const Matrix2x2& B) {
     19   Matrix2x2 out;
     20   for (size_t y = 0; y < 2; ++y) {
     21     for (size_t x = 0; x < 2; ++x) {
     22       out[y][x] = A[0][x] * B[y][0] + A[1][x] * B[y][1];
     23     }
     24   }
     25   return out;
     26 }
     27 
     28 Matrix2x2 Transpose(const Matrix2x2& A) {
     29   return {{{A[0][0], A[1][0]}, {A[0][1], A[1][1]}}};
     30 }
     31 
     32 Matrix2x2 RandomSymmetricMatrix(Rng& rng, const double vmin,
     33                                 const double vmax) {
     34   Matrix2x2 A;
     35   A[0][0] = rng.UniformF(vmin, vmax);
     36   A[0][1] = A[1][0] = rng.UniformF(vmin, vmax);
     37   A[1][1] = rng.UniformF(vmin, vmax);
     38   return A;
     39 }
     40 
     41 void VerifyMatrixEqual(const Matrix2x2& A, const Matrix2x2& B,
     42                        const double eps) {
     43   for (size_t y = 0; y < 2; ++y) {
     44     for (size_t x = 0; x < 2; ++x) {
     45       ASSERT_NEAR(A[y][x], B[y][x], eps);
     46     }
     47   }
     48 }
     49 
     50 void VerifyOrthogonal(const Matrix2x2& A, const double eps) {
     51   VerifyMatrixEqual(Identity(), MatMul(Transpose(A), A), eps);
     52 }
     53 
     54 TEST(LinAlgTest, ConvertToDiagonal) {
     55   {
     56     Matrix2x2 I = Identity();
     57     Matrix2x2 U;
     58     Vector2 d;
     59     ConvertToDiagonal(I, d, U);
     60     VerifyMatrixEqual(I, U, 1e-15);
     61     for (size_t k = 0; k < 2; ++k) {
     62       ASSERT_NEAR(d[k], 1.0, 1e-15);
     63     }
     64   }
     65   {
     66     Matrix2x2 A = Identity();
     67     A[0][1] = A[1][0] = 2.0;
     68     Matrix2x2 U;
     69     Vector2 d;
     70     ConvertToDiagonal(A, d, U);
     71     VerifyOrthogonal(U, 1e-12);
     72     VerifyMatrixEqual(A, MatMul(U, MatMul(Diagonal(d), Transpose(U))), 1e-12);
     73   }
     74   Rng rng(0);
     75   for (size_t i = 0; i < 100; ++i) {
     76     Matrix2x2 A = RandomSymmetricMatrix(rng, -1.0, 1.0);
     77     Matrix2x2 U;
     78     Vector2 d;
     79     ConvertToDiagonal(A, d, U);
     80     VerifyOrthogonal(U, 1e-12);
     81     VerifyMatrixEqual(A, MatMul(U, MatMul(Diagonal(d), Transpose(U))), 1e-12);
     82   }
     83 }
     84 
     85 }  // namespace
     86 }  // namespace jxl