41 lines
679 B
C++
41 lines
679 B
C++
#include <cmath>
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#include "nr.h"
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using namespace std;
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DP NR::rtflsp(DP func(const DP), const DP x1, const DP x2, const DP xacc)
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{
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const int MAXIT=30;
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int j;
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DP fl,fh,xl,xh,dx,del,f,rtf;
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fl=func(x1);
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fh=func(x2);
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if (fl*fh > 0.0) nrerror("Root must be bracketed in rtflsp");
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if (fl < 0.0) {
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xl=x1;
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xh=x2;
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} else {
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xl=x2;
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xh=x1;
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SWAP(fl,fh);
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}
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dx=xh-xl;
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for (j=0;j<MAXIT;j++) {
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rtf=xl+dx*fl/(fl-fh);
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f=func(rtf);
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if (f < 0.0) {
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del=xl-rtf;
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xl=rtf;
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fl=f;
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} else {
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del=xh-rtf;
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xh=rtf;
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fh=f;
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}
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dx=xh-xl;
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if (fabs(del) < xacc || f == 0.0) return rtf;
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}
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nrerror("Maximum number of iterations exceeded in rtflsp");
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return 0.0;
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}
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