/* statistics/mean_source.c

 * 

 * Copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 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 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, mean) (const BASE data[], const size_t stride, const size_t size)

{

  /* Compute the arithmetic mean of a dataset using the recurrence relation 

     mean_(n) = mean(n-1) + (data[n] - mean(n-1))/(n+1)   */

  long double mean = 0;

  size_t i;

  for (i = 0; i < size; i++)

    {

      mean += (data[i * stride] - mean) / (i + 1);

    }

  return mean;

}