diff options
Diffstat (limited to 'libavutil/lfg.c')
| -rw-r--r-- | libavutil/lfg.c | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/libavutil/lfg.c b/libavutil/lfg.c index 4221e6228b..5ffd76f181 100644 --- a/libavutil/lfg.c +++ b/libavutil/lfg.c @@ -2,20 +2,20 @@ * Lagged Fibonacci PRNG * Copyright (c) 2008 Michael Niedermayer * - * This file is part of Libav. + * This file is part of FFmpeg. * - * Libav is free software; you can redistribute it and/or + * 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. * - * Libav is distributed in the hope that it will be useful, + * 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 Libav; if not, write to the Free Software + * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ @@ -72,8 +72,10 @@ int main(void) av_lfg_init(&state, 0xdeadbeef); for (j = 0; j < 10000; j++) { START_TIMER - for (i = 0; i < 624; i++) + 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); @@ -82,17 +84,33 @@ int main(void) { 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", - bmg_out[0] * stddev + mean, - bmg_out[1] * stddev + mean); + 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; |