85 lines
1.6 KiB
C
85 lines
1.6 KiB
C
/* Copyright 2015 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#include "common.h"
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#include "mat44.h"
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#include "math.h"
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#include "util.h"
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#define K_EPSILON 1E-5f
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void mat44_fp_decompose_lup(mat44_fp_t LU, sizev4_t pivot)
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{
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const size_t N = 4;
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size_t i, j, k;
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for (k = 0; k < N; ++k) {
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fp_t max = fp_abs(LU[k][k]);
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pivot[k] = k;
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for (j = k + 1; j < N; ++j) {
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const fp_t lu_jk = fp_abs(LU[j][k]);
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if (max < lu_jk) {
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max = lu_jk;
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pivot[k] = j;
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}
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}
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if (pivot[k] != k)
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mat44_fp_swap_rows(LU, k, pivot[k]);
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if (fp_abs(LU[k][k]) < FLOAT_TO_FP(K_EPSILON))
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continue;
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for (j = k + 1; j < N; ++j)
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LU[k][j] = fp_div_dbz(LU[k][j], LU[k][k]);
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for (i = k + 1; i < N; ++i)
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for (j = k + 1; j < N; ++j)
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LU[i][j] -= fp_mul(LU[i][k], LU[k][j]);
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}
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}
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void mat44_fp_swap_rows(mat44_fp_t A, const size_t i, const size_t j)
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{
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const size_t N = 4;
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size_t k;
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if (i == j)
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return;
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for (k = 0; k < N; ++k) {
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fp_t tmp = A[i][k];
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A[i][k] = A[j][k];
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A[j][k] = tmp;
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}
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}
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void mat44_fp_solve(mat44_fp_t A, fpv4_t x, const fpv4_t b,
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const sizev4_t pivot)
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{
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const size_t N = 4;
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fpv4_t b_copy;
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size_t i, k;
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memcpy(b_copy, b, sizeof(fpv4_t));
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for (k = 0; k < N; ++k) {
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if (pivot[k] != k) {
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fp_t tmp = b_copy[k];
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b_copy[k] = b_copy[pivot[k]];
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b_copy[pivot[k]] = tmp;
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}
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x[k] = b_copy[k];
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for (i = 0; i < k; ++i)
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x[k] -= fp_mul(x[i], A[k][i]);
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x[k] = fp_div_dbz(x[k], A[k][k]);
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}
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for (k = N; k-- > 0;)
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for (i = k + 1; i < N; ++i)
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x[k] -= fp_mul(x[i], A[k][i]);
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}
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