37 lines
2.4 KiB
C
37 lines
2.4 KiB
C
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "dsp/core/core.h"
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#define LEIBNIZ_FORMULA(a, b, c, d, e, f, g, h, i) \
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(a * e * i + b * f * g + c * d * h - c * e * g - b * d * i - a * f * h)
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/**
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* Computes determinant of 3×3 matrix.
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* i.e. how much space is inside the cube
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*
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* @param 𝐀 is input matrix
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* @param 𝑑 is det(𝐀)
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* @return |𝐀| or 0 if degenerate
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*/
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double det3(const double A[3][3]) {
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return LEIBNIZ_FORMULA(A[0][0], A[0][1], A[0][2], A[1][0], A[1][1], A[1][2],
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A[2][0], A[2][1], A[2][2]);
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}
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