diff options
Diffstat (limited to 'gsl-1.9/statistics/variance_source.c')
-rw-r--r-- | gsl-1.9/statistics/variance_source.c | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/gsl-1.9/statistics/variance_source.c b/gsl-1.9/statistics/variance_source.c new file mode 100644 index 0000000..7578a43 --- /dev/null +++ b/gsl-1.9/statistics/variance_source.c @@ -0,0 +1,90 @@ +/* statistics/variance_source.c + * + * Copyright (C) 1996, 1997, 1998, 1999, 2000 Jim Davies, Brian Gough + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or (at + * your option) any later version. + * + * This program 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 + * General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + */ + +static double +FUNCTION(compute,variance) (const BASE data[], const size_t stride, const size_t n, const double mean); + +static double +FUNCTION(compute,variance) (const BASE data[], const size_t stride, const size_t n, const double mean) +{ + /* takes a dataset and finds the variance */ + + long double variance = 0 ; + + size_t i; + + /* find the sum of the squares */ + for (i = 0; i < n; i++) + { + const long double delta = (data[i * stride] - mean); + variance += (delta * delta - variance) / (i + 1); + } + + return variance ; +} + + +double +FUNCTION(gsl_stats,variance_with_fixed_mean) (const BASE data[], const size_t stride, const size_t n, const double mean) +{ + const double variance = FUNCTION(compute,variance) (data, stride, n, mean); + return variance; +} + +double +FUNCTION(gsl_stats,sd_with_fixed_mean) (const BASE data[], const size_t stride, const size_t n, const double mean) +{ + const double variance = FUNCTION(compute,variance) (data, stride, n, mean); + const double sd = sqrt (variance); + + return sd; +} + + + +double +FUNCTION(gsl_stats,variance_m) (const BASE data[], const size_t stride, const size_t n, const double mean) +{ + const double variance = FUNCTION(compute,variance) (data, stride, n, mean); + + return variance * ((double)n / (double)(n - 1)); +} + +double +FUNCTION(gsl_stats,sd_m) (const BASE data[], const size_t stride, const size_t n, const double mean) +{ + const double variance = FUNCTION(compute,variance) (data, stride, n, mean); + const double sd = sqrt (variance * ((double)n / (double)(n - 1))); + + return sd; +} + +double +FUNCTION(gsl_stats,variance) (const BASE data[], const size_t stride, const size_t n) +{ + const double mean = FUNCTION(gsl_stats,mean) (data, stride, n); + return FUNCTION(gsl_stats,variance_m)(data, stride, n, mean); +} + +double +FUNCTION(gsl_stats,sd) (const BASE data[], const size_t stride, const size_t n) +{ + const double mean = FUNCTION(gsl_stats,mean) (data, stride, n); + return FUNCTION(gsl_stats,sd_m) (data, stride, n, mean); +} |