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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_fp_decompose_lup(mat44_fp_t LU, sizev4_t pivot)
{
const size_t N = 4;
size_t i, j, k;
for (k = 0; k < N; ++k) {
fp_t max = fp_abs(LU[k][k]);
pivot[k] = k;
for (j = k + 1; j < N; ++j) {
const fp_t lu_jk = fp_abs(LU[j][k]);
if (max < lu_jk) {
max = lu_jk;
pivot[k] = j;
}
}
if (pivot[k] != k)
mat44_fp_swap_rows(LU, k, pivot[k]);
if (fp_abs(LU[k][k]) < FLOAT_TO_FP(K_EPSILON))
continue;
for (j = k + 1; j < N; ++j)
LU[k][j] = fp_div_dbz(LU[k][j], LU[k][k]);
for (i = k + 1; i < N; ++i)
for (j = k + 1; j < N; ++j)
LU[i][j] -= fp_mul(LU[i][k], LU[k][j]);
}
}
void mat44_fp_swap_rows(mat44_fp_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) {
fp_t tmp = A[i][k];
A[i][k] = A[j][k];
A[j][k] = tmp;
}
}
void mat44_fp_solve(mat44_fp_t A, fpv4_t x, const fpv4_t b,
const sizev4_t pivot)
{
const size_t N = 4;
fpv4_t b_copy;
size_t i, k;
memcpy(b_copy, b, sizeof(fpv4_t));
for (k = 0; k < N; ++k) {
if (pivot[k] != k) {
fp_t 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] -= fp_mul(x[i], A[k][i]);
x[k] = fp_div_dbz(x[k], A[k][k]);
}
for (k = N; k-- > 0;)
for (i = k + 1; i < N; ++i)
x[k] -= fp_mul(x[i], A[k][i]);
}
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