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/* Copyright 2015 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "common.h"
#include "mat44.h"
#include "math.h"
#include "util.h"
#define K_EPSILON 1E-5f
void mat44_float_decompose_lup(mat44_float_t LU, sizev4_t pivot)
{
const size_t N = 4;
size_t i, j, k;
for (k = 0; k < N; ++k) {
float max = fabsf(LU[k][k]);
pivot[k] = k;
for (j = k + 1; j < N; ++j) {
if (max < fabsf(LU[j][k])) {
max = fabsf(LU[j][k]);
pivot[k] = j;
}
}
if (pivot[k] != k)
mat44_float_swap_rows(LU, k, pivot[k]);
if (fabsf(LU[k][k]) < K_EPSILON)
continue;
for (j = k + 1; j < N; ++j)
LU[k][j] /= LU[k][k];
for (i = k + 1; i < N; ++i)
for (j = k + 1; j < N; ++j)
LU[i][j] -= LU[i][k] * LU[k][j];
}
}
void mat44_float_swap_rows(mat44_float_t A, const size_t i, const size_t j)
{
const size_t N = 4;
size_t k;
if (i == j)
return;
for (k = 0; k < N; ++k) {
float tmp = A[i][k];
A[i][k] = A[j][k];
A[j][k] = tmp;
}
}
void mat44_float_solve(mat44_float_t A, floatv4_t x, const floatv4_t b,
const sizev4_t pivot)
{
const size_t N = 4;
floatv4_t b_copy;
size_t i, k;
memcpy(b_copy, b, sizeof(floatv4_t));
for (k = 0; k < N; ++k) {
if (pivot[k] != k) {
float tmp = b_copy[k];
b_copy[k] = b_copy[pivot[k]];
b_copy[pivot[k]] = tmp;
}
x[k] = b_copy[k];
for (i = 0; i < k; ++i)
x[k] -= x[i] * A[k][i];
x[k] /= A[k][k];
}
for (k = N; k-- > 0;)
for (i = k + 1; i < N; ++i)
x[k] -= x[i] * A[k][i];
}
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