37 lines
766 B
C++
37 lines
766 B
C++
#include <cmath>
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#include "nr.h"
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using namespace std;
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void NR::qroot(Vec_I_DP &p, DP &b, DP &c, const DP eps)
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{
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const int ITMAX=20;
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const DP TINY=1.0e-14;
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int iter;
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DP sc,sb,s,rc,rb,r,dv,delc,delb;
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Vec_DP d(3);
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int n=p.size()-1;
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Vec_DP q(n+1),qq(n+1),rem(n+1);
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d[2]=1.0;
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for (iter=0;iter<ITMAX;iter++) {
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d[1]=b;
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d[0]=c;
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poldiv(p,d,q,rem);
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s=rem[0];
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r=rem[1];
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poldiv(q,d,qq,rem);
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sb = -c*(rc = -rem[1]);
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rb = -b*rc+(sc = -rem[0]);
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dv=1.0/(sb*rc-sc*rb);
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delb=(r*sc-s*rc)*dv;
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delc=(-r*sb+s*rb)*dv;
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b += (delb=(r*sc-s*rc)*dv);
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c += (delc=(-r*sb+s*rb)*dv);
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if ((fabs(delb) <= eps*fabs(b) || fabs(b) < TINY)
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&& (fabs(delc) <= eps*fabs(c) || fabs(c) < TINY)) {
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return;
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}
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}
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nrerror("Too many iterations in routine qroot");
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}
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