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weight.c
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1/******************************************************************************
2
3 Copyright (c) 2005,2008 Turku PET Centre
4
5 File: weight.c
6 Description: Functions for setting weight factors based on SIF.
7
8 This library is free software; you can redistribute it and/or
9 modify it under the terms of the GNU Lesser General Public
10 License as published by the Free Software Foundation; either
11 version 2.1 of the License, or (at your option) any later version.
12
13 This library is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
16 See the GNU Lesser General Public License for more details:
17 http://www.gnu.org/copyleft/lesser.html
18
19 You should have received a copy of the GNU Lesser General Public License
20 along with this library/program; if not, write to the Free Software
21 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22
23 Turku PET Centre, Turku, Finland, http://www.turkupetcentre.fi
24
25 Modification history:
26 2005-01-15 Vesa Oikonen
27 First created. Functions from sif.c.
28 2005-01-16 VO
29 Weights are scaled so that average is 1.0.
30 2005-04-26 CL
31 Merged libsif to libtpcimgio.
32 2008-07-11 VO
33 Added sifModerate().
34
35******************************************************************************/
36
37/*****************************************************************************/
38#include "sif.h"
39/*****************************************************************************/
40
41/*****************************************************************************/
61void sifWeight(SIF *data, double halflife) {
62 int i;
63 double f, d;
64
65 if(SIF_TEST) printf("sifWeight(*sif, %g)\n", halflife);
66 /* Calculate weights */
67 for(i=0; i<data->frameNr; i++) {
68 if(data->trues[i]<1.0) data->trues[i]=1.0;
69 f=data->x2[i]-data->x1[i]; if(f<=0.0) f=1.0;
70 if(halflife<=1.0E-8)
71 d=1.0;
72 else
73 d=exp( ((data->x1[i]+data->x2[i])/2.0)*0.693147/halflife );
74 data->weights[i]=(f*f)/(d*data->trues[i]);
75 /*printf("%3d %g %g\n", i, data->trues[i], data->weights[i]);*/
76 }
77
78#if(0)
79 /* Scale weights between [0,1] */
80 f=data->weights[0];
81 for(i=1; i<data->frameNr; i++) if(data->weights[i]>f) f=data->weights[i];
82 for(i=0; i<data->frameNr; i++) data->weights[i]/=f;
83#else
84 /* Scale weights so that average weight is 1.0 */
85 for(i=0, f=0.0; i<data->frameNr; i++) f+=data->weights[i];
86 f/=(double)data->frameNr;
87 for(i=0; i<data->frameNr; i++) data->weights[i]/=f;
88#endif
89
90 return;
91}
92/*****************************************************************************/
93
94/*****************************************************************************/
104 SIF *sif,
106 double limit
107) {
108 int fi;
109 double w, f;
110
111 if(sif==NULL || sif->frameNr<2) return;
112 if(limit<=1.0) return;
113 for(w=f=sif->trues[0], fi=1; fi<sif->frameNr; fi++) {
114 if(sif->trues[fi]>w) w=sif->trues[fi];
115 else if(sif->trues[fi]<f) f=sif->trues[fi];
116 }
117 if(f*limit<w) {
118 for(w/=limit, fi=0; fi<sif->frameNr; fi++)
119 if(sif->trues[fi]>0.0) sif->trues[fi]+=w; else sif->trues[fi]=w;
120 } else {
121 for(fi=0; fi<sif->frameNr; fi++)
122 if(sif->trues[fi]<0.0) sif->trues[fi]=0.0;
123 }
124}
125/*****************************************************************************/
126
127/*****************************************************************************/
128
int SIF_TEST
Definition: sif.h:63
Definition: sif.h:36
double * x1
Definition: sif.h:50
int frameNr
Definition: sif.h:40
double * x2
Definition: sif.h:52
double * weights
Definition: sif.h:60
double * trues
Definition: sif.h:58
void sifModerate(SIF *sif, double limit)
Definition: weight.c:102
void sifWeight(SIF *data, double halflife)
Definition: weight.c:61