32 lines
519 B
C++
32 lines
519 B
C++
#include <cmath>
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#include "nr.h"
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using namespace std;
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DP NR::rtsec(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,f,dx,xl,rts;
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fl=func(x1);
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f=func(x2);
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if (fabs(fl) < fabs(f)) {
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rts=x1;
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xl=x2;
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SWAP(fl,f);
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} else {
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xl=x1;
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rts=x2;
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}
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for (j=0;j<MAXIT;j++) {
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dx=(xl-rts)*f/(f-fl);
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xl=rts;
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fl=f;
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rts += dx;
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f=func(rts);
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if (fabs(dx) < xacc || f == 0.0) return rts;
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}
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nrerror("Maximum number of iterations exceeded in rtsec");
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return 0.0;
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}
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