| /* |
| * 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" |
| |
| static const double Z_TABLE[31][10] = { |
| {0.5000, 0.5040, 0.5080, 0.5120, 0.5160, 0.5199, 0.5239, 0.5279, 0.5319, 0.5359}, |
| {0.5398, 0.5438, 0.5478, 0.5517, 0.5557, 0.5596, 0.5636, 0.5675, 0.5714, 0.5753}, |
| {0.5793, 0.5832, 0.5871, 0.5910, 0.5948, 0.5987, 0.6026, 0.6064, 0.6103, 0.6141}, |
| {0.6179, 0.6217, 0.6255, 0.6293, 0.6331, 0.6368, 0.6406, 0.6443, 0.6480, 0.6517}, |
| {0.6554, 0.6591, 0.6628, 0.6664, 0.6700, 0.6736, 0.6772, 0.6808, 0.6844, 0.6879}, |
| {0.6915, 0.6950, 0.6985, 0.7019, 0.7054, 0.7088, 0.7123, 0.7157, 0.7190, 0.7224}, |
| {0.7257, 0.7291, 0.7324, 0.7357, 0.7389, 0.7422, 0.7454, 0.7486, 0.7517, 0.7549}, |
| {0.7580, 0.7611, 0.7642, 0.7673, 0.7704, 0.7734, 0.7764, 0.7794, 0.7823, 0.7852}, |
| {0.7881, 0.7910, 0.7939, 0.7967, 0.7995, 0.8023, 0.8051, 0.8078, 0.8106, 0.8133}, |
| {0.8159, 0.8186, 0.8212, 0.8238, 0.8264, 0.8289, 0.8315, 0.8340, 0.8365, 0.8389}, |
| {0.8413, 0.8438, 0.8461, 0.8485, 0.8508, 0.8531, 0.8554, 0.8577, 0.8599, 0.8621}, |
| {0.8643, 0.8665, 0.8686, 0.8708, 0.8729, 0.8749, 0.8770, 0.8790, 0.8810, 0.8830}, |
| {0.8849, 0.8869, 0.8888, 0.8907, 0.8925, 0.8944, 0.8962, 0.8980, 0.8997, 0.9015}, |
| {0.9032, 0.9049, 0.9066, 0.9082, 0.9099, 0.9115, 0.9131, 0.9147, 0.9162, 0.9177}, |
| {0.9192, 0.9207, 0.9222, 0.9236, 0.9251, 0.9265, 0.9279, 0.9292, 0.9306, 0.9319}, |
| {0.9332, 0.9345, 0.9357, 0.9370, 0.9382, 0.9394, 0.9406, 0.9418, 0.9429, 0.9441}, |
| {0.9452, 0.9463, 0.9474, 0.9484, 0.9495, 0.9505, 0.9515, 0.9525, 0.9535, 0.9545}, |
| {0.9554, 0.9564, 0.9573, 0.9582, 0.9591, 0.9599, 0.9608, 0.9616, 0.9625, 0.9633}, |
| {0.9641, 0.9649, 0.9656, 0.9664, 0.9671, 0.9678, 0.9686, 0.9693, 0.9699, 0.9706}, |
| {0.9713, 0.9719, 0.9726, 0.9732, 0.9738, 0.9744, 0.9750, 0.9756, 0.9761, 0.9767}, |
| {0.9772, 0.9778, 0.9783, 0.9788, 0.9793, 0.9798, 0.9803, 0.9808, 0.9812, 0.9817}, |
| {0.9821, 0.9826, 0.9830, 0.9834, 0.9838, 0.9842, 0.9846, 0.9850, 0.9854, 0.9857}, |
| {0.9861, 0.9864, 0.9868, 0.9871, 0.9875, 0.9878, 0.9881, 0.9884, 0.9887, 0.9890}, |
| {0.9893, 0.9896, 0.9898, 0.9901, 0.9904, 0.9906, 0.9909, 0.9911, 0.9913, 0.9916}, |
| {0.9918, 0.9920, 0.9922, 0.9925, 0.9927, 0.9929, 0.9931, 0.9932, 0.9934, 0.9936}, |
| {0.9938, 0.9940, 0.9941, 0.9943, 0.9945, 0.9946, 0.9948, 0.9949, 0.9951, 0.9952}, |
| {0.9953, 0.9955, 0.9956, 0.9957, 0.9959, 0.9960, 0.9961, 0.9962, 0.9963, 0.9964}, |
| {0.9965, 0.9966, 0.9967, 0.9968, 0.9969, 0.9970, 0.9971, 0.9972, 0.9973, 0.9974}, |
| {0.9974, 0.9975, 0.9976, 0.9977, 0.9977, 0.9978, 0.9979, 0.9979, 0.9980, 0.9981}, |
| {0.9981, 0.9982, 0.9982, 0.9983, 0.9984, 0.9984, 0.9985, 0.9985, 0.9986, 0.9986}, |
| {0.9987, 0.9987, 0.9987, 0.9988, 0.9988, 0.9989, 0.9989, 0.9989, 0.9990, 0.9990} }; |
| |
| // Inverse cumulative distribution function |
| static double inv_cdf(double u) |
| { |
| const double a[4] = { 2.50662823884, |
| -18.61500062529, |
| 41.39119773534, |
| -25.44106049637}; |
| |
| const double b[4] = {-8.47351093090, |
| 23.08336743743, |
| -21.06224101826, |
| 3.13082909833}; |
| |
| const double c[9] = {0.3374754822726147, |
| 0.9761690190917186, |
| 0.1607979714918209, |
| 0.0276438810333863, |
| 0.0038405729373609, |
| 0.0003951896511919, |
| 0.0000321767881768, |
| 0.0000002888167364, |
| 0.0000003960315187}; |
| |
| double r; |
| double x = u - 0.5; |
| |
| // Beasley-Springer |
| if (fabs(x) < 0.42) { |
| |
| double y = x * x; |
| r = x * (((a[3]*y+a[2])*y+a[1])*y+a[0]) / |
| ((((b[3]*y+b[2])*y+b[1])*y+b[0])*y+1.0); |
| } |
| else {// Moro |
| r = u; |
| if (x > 0.0) |
| r = 1.0 - u; |
| r = log(-log(r)); |
| r = c[0] + r*(c[1]+r*(c[2]+r*(c[3]+r*(c[4]+r*(c[5]+r*(c[6]+ |
| r*(c[7]+r*c[8]))))))); |
| if (x < 0.0) |
| r = -r; |
| } |
| |
| return r; |
| } |
| int main(void) |
| { |
| int x = 0; |
| int i, j; |
| AVLFG state; |
| av_lfg_init(&state, 0xdeadbeef); |
| for (j = 0; j < 10000; j++) { |
| for (i = 0; i < 624; i++) { |
| //av_log(NULL, AV_LOG_ERROR, "%X\n", av_lfg_get(&state)); |
| x += av_lfg_get(&state); |
| } |
| } |
| 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, QH = 0; |
| double Z, p_value = -1, tot_samp = 1000; |
| double *PRN_arr = av_malloc_array(tot_samp, sizeof(double)); |
| |
| if (!PRN_arr) { |
| fprintf(stderr, "failed to allocate memory!\n"); |
| return 1; |
| } |
| |
| av_lfg_init(&state, 42); |
| for (i = 0; i < tot_samp; i += 2) { |
| double bmg_out[2]; |
| av_bmg_get(&state, bmg_out); |
| PRN_arr[i ] = bmg_out[0] * stddev + mean; |
| PRN_arr[i+1] = bmg_out[1] * stddev + mean; |
| samp_mean += PRN_arr[i] + PRN_arr[i+1]; |
| samp_stddev += PRN_arr[i] * PRN_arr[i] + PRN_arr[i+1] * PRN_arr[i+1]; |
| printf("PRN%d : %f\n" |
| "PRN%d : %f\n", |
| i, PRN_arr[i], i+1, PRN_arr[i+1]); |
| } |
| samp_mean /= tot_samp; |
| samp_stddev /= (tot_samp - 1); |
| samp_stddev -= (tot_samp * 1.0 / (tot_samp - 1))*samp_mean*samp_mean; |
| samp_stddev = sqrt(samp_stddev); |
| Z = (mean - samp_mean) / (stddev / sqrt(tot_samp)); |
| { |
| int x, y, a, b, flag = 0; |
| |
| if (Z < 0.0) { |
| flag = !flag; |
| Z = Z * -1.0; |
| } |
| |
| a = (int)(Z * 100); |
| b = ((int)Z * 100); |
| x = Z * 10; |
| y = (b > 0) ? a % b : a; |
| y = y % 10; |
| if (x > 30 || y > 9) { |
| av_log(NULL, AV_LOG_INFO, "error: out of bounds! tried to access" |
| "Z_TABLE[%d][%d]\n", x, y); |
| goto SKIP; |
| } |
| p_value = flag ? 1 - Z_TABLE[x][y] : Z_TABLE[x][y]; |
| } |
| |
| SKIP: for (i = 0; i < tot_samp; ++i) { |
| |
| if ( i < (tot_samp - 1)) { |
| double H_diff; |
| H_diff = inv_cdf((i + 2.0 - (3.0/8.0)) / (tot_samp + (1.0/4.0))); |
| H_diff -= inv_cdf((i + 1.0 - (3.0/8.0)) / (tot_samp + (1.0/4.0))); |
| |
| QH += ((PRN_arr[i + 1] - PRN_arr[i]) / H_diff); |
| } |
| } |
| QH = 1.0 - QH / ((tot_samp - 1.0) * samp_stddev); |
| |
| printf("sample mean : %f\n" |
| "true mean : %f\n" |
| "sample stddev: %f\n" |
| "true stddev : %f\n" |
| "z-score : %f\n" |
| "p-value : %f\n" |
| "QH[normality]: %f\n", |
| samp_mean, mean, samp_stddev, stddev, Z, p_value, QH); |
| |
| av_freep(&PRN_arr); |
| } |
| return 0; |
| } |
