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42 lines
1.2 KiB
C
42 lines
1.2 KiB
C
/*
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* Matrix operations library
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*
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* Copyright (C) 1999-2000
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* Thomas Sailer, <sailer@ife.ee.ethz.ch>
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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; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "mat.h"
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#include <stdlib.h>
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/*
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* Approximation of a normally distributed random number generator
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* with unit variance
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*
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* division factor: randommax * sqrt(nrand / 12)
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* with nrand = 16 and randommax = 0x1000
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*/
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float randn(void)
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{
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int sum = 0, i;
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for (i = 0; i < 16; i++)
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sum += random() & 0xfff;
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return (sum - 0x8000) * (1.0 / 4729.7);
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}
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