2 ***********************************************************
3 $SNARK_Header: S N A R K 1 4 - A PICTURE RECONSTRUCTION PROGRAM $
4 $HeadURL: svn://dig.cs.gc.cuny.edu/snark/trunk/src/snark/quad_back.cpp $
5 $LastChangedRevision: 80 $
6 $Date: 2014-07-01 21:01:54 -0400 (Tue, 01 Jul 2014) $
8 ***********************************************************
10 THE BACK PROJECTIONS ARE STORED IN X AFTER CORRECTION TO AVRDEN
23 void quad_class::back(REAL* x, INTEGER* list, REAL* weight)
28 REAL dum; // what is this variable for?? hstau
38 for (i = 0; i < GeoPar.area; i++)
43 // COMPUTE BACK PROJECTION
48 for (np = 0; np < GeoPar.prjnum; np++)
50 dum = Anglst.prdta(np, 1); // should be Anglst.prdta(np, 0)? hstau
51 for (nr = 0; nr < GeoPar.nrays; nr++)
53 wray(np, nr, list, weight, &numb, &snorm);
56 for (nb = 0; nb < numb; nb++)
59 x[ky] += Anglst.prdta(np, nr) * weight[nb];
64 zn = (REAL) 1.0 / ((REAL) (GeoPar.prjnum));
68 for (np = 0; np < GeoPar.prjnum; np++)
70 dum = Anglst.prdta(np, 1);
71 for (nr = 0; nr < GeoPar.nrays; nr++)
73 ray(np, nr, list, weight, &numb, &snorm);
76 for (nb = 0; nb < numb; nb++)
79 x[ky] += Anglst.prdta(np, nr);
85 zn = (GeoPar.pixsiz * GeoPar.pixsiz) / ((REAL) (GeoPar.prjnum));
90 for (i = 0; i < GeoPar.area; i++)