137 lines
3.1 KiB
C
137 lines
3.1 KiB
C
/* @(#) Calculates the mean and the standard deviation (std) of
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* @(#) an int or double buffer of size size.
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* @(#)
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* @(#) Usage:
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* @(#) int im__mean_std_double_buffer(buffer, size, pmean, pstd)
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* @(#) double *buffer;
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* @(#) int size;
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* @(#) double *pmean, *pstd;
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* @(#)
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* @(#) int im__mean_std_int_buffer(buffer, size, pmean, pstd)
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* @(#) int *buffer;
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* @(#) int size;
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* @(#) double *pmean, *pstd;
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* @(#)
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* @(#) Both functions return 0 on success and -1 on error
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*
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* Copyright: N. Dessipris 1991
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* Written on: 2/12/1991
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* Updated on: 2/12/1991
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* 22/7/93 JC
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* - externs removed
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <vips/vips.h>
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#ifdef WITH_DMALLOC
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#include <dmalloc.h>
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#endif /*WITH_DMALLOC*/
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int
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im__mean_std_double_buffer( double *buffer, int size,
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double *pmean, double *pstd )
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{
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double mean, std;
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register int i;
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double sumf;
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double temp;
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double *pbuffer;
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double sumf2;
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double correction; /* calulates the correction term for the variance */
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double variance; /* = (sumf2 - correction)/n */
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if (size <= 0) {
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im_errormsg("im_mean_std_double_buffer: wrong args");
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return(-1);
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}
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mean = 0.0; std = 0.0;
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sumf = 0.0; sumf2 = 0.0;
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pbuffer = buffer;
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for (i=0; i<size; i++) {
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temp = *pbuffer++;
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sumf += temp;
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sumf2 += (temp*temp);
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}
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correction = (sumf * sumf)/((double)size);
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mean = sumf/((double)size);
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variance = ( sumf2 - correction)/((double)size);
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std = sqrt(variance);
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*pmean = mean;
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*pstd = std;
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return( 0 );
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}
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int
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im__mean_std_int_buffer( int *buffer, int size,
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double *pmean, double *pstd )
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{
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double mean, std;
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register int i;
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int sumf;
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int temp;
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int *pbuffer;
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int sumf2;
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double correction; /* calulates the correction term for the variance */
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double variance; /* = (sumf2 - correction)/n */
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if (size <= 0) {
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im_errormsg("im_mean_std_int_buffer: wrong args");
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return(-1);
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}
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mean = 0.0; std = 0.0;
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sumf = 0; sumf2 = 0;
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pbuffer = buffer;
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for (i=0; i<size; i++) {
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temp = *pbuffer++;
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sumf += temp;
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sumf2 += (temp*temp);
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}
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correction = ((double)(sumf * sumf))/((double)size);
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mean = ((double)sumf)/((double)size);
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variance = ( sumf2 - correction)/((double)size);
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std = sqrt(variance);
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*pmean = mean;
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*pstd = std;
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return(0);
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}
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