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828b55a735
Code for hard iron calibration: Every seconds (or faster if enough samples), find a sphere that fit the compass data. Based on Android code. BRANCH=smaug BUG=chrome-os-partner:39900 TEST=Check hard-iron bias is removed. Works better outside. Change-Id: Iab479d5113b6560b4f01b0fd87373d2eecdb9b54 Signed-off-by: Gwendal Grignou <gwendal@chromium.org> Reviewed-on: https://chromium-review.googlesource.com/299583 Reviewed-by: Anton Staaf <robotboy@chromium.org>
86 lines
1.5 KiB
C
86 lines
1.5 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_decompose_lup(mat44_t LU, size4_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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float max = fabsf(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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if (max < fabsf(LU[j][k])) {
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max = fabsf(LU[j][k]);
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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_swap_rows(LU, k, pivot[k]);
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if (fabsf(LU[k][k]) < 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] /= 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] -= LU[i][k] * LU[k][j];
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}
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}
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void mat44_swap_rows(mat44_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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float 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_solve(mat44_t A, vec4_t x, const vec4_t b, const size4_t pivot)
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{
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const size_t N = 4;
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vec4_t b_copy;
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size_t i, k;
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memcpy(b_copy, b, sizeof(vec4_t));
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for (k = 0; k < N; ++k) {
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if (pivot[k] != k) {
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float 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] -= x[i] * A[k][i];
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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] -= x[i] * A[k][i];
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}
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