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/* statistics/trmean_source.c
*
* Copyright (C) 2018 Patrick Alken
*
* 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 3 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.
*/
double
FUNCTION (gsl_stats, trmean_from_sorted_data) (const double trim, const BASE sorted_data[],
const size_t stride, const size_t size)
{
if (trim >= 0.5)
{
return FUNCTION(gsl_stats, median_from_sorted_data)(sorted_data, stride, size);
}
else
{
size_t ilow = (size_t) floor(trim * size);
size_t ihigh = size - ilow - 1;
double mean = 0.0;
double k = 0.0;
size_t i;
/* compute mean of middle samples in [ilow,ihigh] */
for (i = ilow; i <= ihigh; ++i)
{
double delta = sorted_data[i * stride] - mean;
k += 1.0;
mean += delta / k;
}
return mean;
}
}
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