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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#ifndef LIB_JXL_MATRIX_OPS_H_
#define LIB_JXL_MATRIX_OPS_H_
// 3x3 matrix operations.
#include <cmath> // abs
#include <cstddef>
#include "lib/jxl/base/status.h"
namespace jxl {
// Computes C = A * B, where A, B, C are 3x3 matrices.
template <typename T>
void Mul3x3Matrix(const T* a, const T* b, T* c) {
alignas(16) T temp[3]; // For transposed column
for (size_t x = 0; x < 3; x++) {
for (size_t z = 0; z < 3; z++) {
temp[z] = b[z * 3 + x];
}
for (size_t y = 0; y < 3; y++) {
double e = 0;
for (size_t z = 0; z < 3; z++) {
e += a[y * 3 + z] * temp[z];
}
c[y * 3 + x] = e;
}
}
}
// Computes C = A * B, where A is 3x3 matrix and B is vector.
template <typename T>
void Mul3x3Vector(const T* a, const T* b, T* c) {
for (size_t y = 0; y < 3; y++) {
double e = 0;
for (size_t x = 0; x < 3; x++) {
e += a[y * 3 + x] * b[x];
}
c[y] = e;
}
}
// Inverts a 3x3 matrix in place.
template <typename T>
Status Inv3x3Matrix(T* matrix) {
// Intermediate computation is done in double precision.
double temp[9];
temp[0] = static_cast<double>(matrix[4]) * matrix[8] -
static_cast<double>(matrix[5]) * matrix[7];
temp[1] = static_cast<double>(matrix[2]) * matrix[7] -
static_cast<double>(matrix[1]) * matrix[8];
temp[2] = static_cast<double>(matrix[1]) * matrix[5] -
static_cast<double>(matrix[2]) * matrix[4];
temp[3] = static_cast<double>(matrix[5]) * matrix[6] -
static_cast<double>(matrix[3]) * matrix[8];
temp[4] = static_cast<double>(matrix[0]) * matrix[8] -
static_cast<double>(matrix[2]) * matrix[6];
temp[5] = static_cast<double>(matrix[2]) * matrix[3] -
static_cast<double>(matrix[0]) * matrix[5];
temp[6] = static_cast<double>(matrix[3]) * matrix[7] -
static_cast<double>(matrix[4]) * matrix[6];
temp[7] = static_cast<double>(matrix[1]) * matrix[6] -
static_cast<double>(matrix[0]) * matrix[7];
temp[8] = static_cast<double>(matrix[0]) * matrix[4] -
static_cast<double>(matrix[1]) * matrix[3];
double det = matrix[0] * temp[0] + matrix[1] * temp[3] + matrix[2] * temp[6];
if (std::abs(det) < 1e-10) {
return JXL_FAILURE("Matrix determinant is too close to 0");
}
double idet = 1.0 / det;
for (size_t i = 0; i < 9; i++) {
matrix[i] = temp[i] * idet;
}
return true;
}
} // namespace jxl
#endif // LIB_JXL_MATRIX_OPS_H_
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