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/*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "libavutil/log.h"
#include "libavutil/timer.h"
#include "libavutil/lfg.h"
int main(void)
{
int x = 0;
int i, j;
AVLFG state;
av_lfg_init(&state, 0xdeadbeef);
for (j = 0; j < 10000; j++) {
START_TIMER
for (i = 0; i < 624; i++) {
//av_log(NULL, AV_LOG_ERROR, "%X\n", av_lfg_get(&state));
x += av_lfg_get(&state);
}
STOP_TIMER("624 calls of av_lfg_get");
}
av_log(NULL, AV_LOG_ERROR, "final value:%X\n", x);
/* BMG usage example */
{
double mean = 1000;
double stddev = 53;
double samp_mean = 0.0, samp_stddev = 0.0;
double samp0, samp1;
av_lfg_init(&state, 42);
for (i = 0; i < 1000; i += 2) {
double bmg_out[2];
av_bmg_get(&state, bmg_out);
samp0 = bmg_out[0] * stddev + mean;
samp1 = bmg_out[1] * stddev + mean;
samp_mean += samp0 + samp1;
samp_stddev += samp0 * samp0 + samp1 * samp1;
av_log(NULL, AV_LOG_INFO,
"%f\n%f\n",
samp0,
samp1);
}
/* TODO: add proper normality test */
samp_mean /= 1000;
samp_stddev /= 999;
samp_stddev -= (1000.0/999.0)*samp_mean*samp_mean;
samp_stddev = sqrt(samp_stddev);
av_log(NULL, AV_LOG_INFO, "sample mean : %f\n"
"true mean : %f\n"
"sample stddev: %f\n"
"true stddev : %f\n",
samp_mean, mean, samp_stddev, stddev);
}
return 0;
}
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