100 lines
1.9 KiB
C++
100 lines
1.9 KiB
C++
#include "nr.h"
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namespace {
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void mg(const int j, Mat_IO_DP &u, Mat_I_DP &rhs, Vec_Mat_DP_p &rho,
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DP &trerr)
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{
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using namespace NR;
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const int NPRE=1,NPOST=1;
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const DP ALPHA=0.33;
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int jpost,jpre,nc,nf;
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DP dum=-1.0;
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nf=u.nrows();
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nc=(nf+1)/2;
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Mat_DP temp(nf,nf);
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if (j == 0) {
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matadd(rhs,*rho[j],temp);
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slvsm2(u,temp);
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} else {
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Mat_DP v(nc,nc),ut(nc,nc),tau(nc,nc),tempc(nc,nc);
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for (jpre=0;jpre<NPRE;jpre++) {
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if (trerr < 0.0) {
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matadd(rhs,*rho[j],temp);
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relax2(u,temp);
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}
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else
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relax2(u,*rho[j]);
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}
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rstrct(ut,u);
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copy(v,ut);
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lop(tau,ut);
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lop(temp,u);
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if (trerr < 0.0)
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matsub(temp,rhs,temp);
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rstrct(tempc,temp);
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matsub(tau,tempc,tau);
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if (trerr > 0.0)
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trerr=ALPHA*anorm2(tau);
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mg(j-1,v,tau,rho,dum);
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matsub(v,ut,tempc);
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interp(temp,tempc);
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matadd(u,temp,u);
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for (jpost=0;jpost<NPOST;jpost++) {
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if (trerr < 0.0) {
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matadd(rhs,*rho[j],temp);
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relax2(u,temp);
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}
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else
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relax2(u,*rho[j]);
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}
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}
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}
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}
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void NR::mgfas(Mat_IO_DP &u, const int maxcyc)
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{
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int j,jcycle,ng=0,ngrid,nn;
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DP res,trerr;
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Mat_DP *uj,*uj1;
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int n=u.nrows();
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nn=n;
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while (nn >>= 1) ng++;
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if ((n-1) != (1 << ng))
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nrerror("n-1 must be a power of 2 in mgfas.");
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Vec_Mat_DP_p rho(ng);
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nn=n;
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ngrid=ng-1;
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rho[ngrid]=new Mat_DP(nn,nn);
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copy(*rho[ngrid],u);
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while (nn > 3) {
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nn=nn/2+1;
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rho[--ngrid]=new Mat_DP(nn,nn);
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rstrct(*rho[ngrid],*rho[ngrid+1]);
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}
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nn=3;
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uj=new Mat_DP(nn,nn);
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slvsm2(*uj,*rho[0]);
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for (j=1;j<ng;j++) {
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nn=2*nn-1;
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uj1=uj;
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uj=new Mat_DP(nn,nn);
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Mat_DP temp(nn,nn);
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interp(*uj,*uj1);
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delete uj1;
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for (jcycle=0;jcycle<maxcyc;jcycle++) {
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trerr=1.0;
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mg(j,*uj,temp,rho,trerr);
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lop(temp,*uj);
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matsub(temp,*rho[j],temp);
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res=anorm2(temp);
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if (res < trerr) break;
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}
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}
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copy(u,*uj);
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delete uj;
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for (j=0;j<ng;j++)
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delete rho[j];
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}
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