23 lines
536 B
C++
23 lines
536 B
C++
#include <cmath>
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#include "nr.h"
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using namespace std;
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DP NR::rtbis(DP func(const DP), const DP x1, const DP x2, const DP xacc)
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{
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const int JMAX=40;
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int j;
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DP dx,f,fmid,xmid,rtb;
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f=func(x1);
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fmid=func(x2);
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if (f*fmid >= 0.0) nrerror("Root must be bracketed for bisection in rtbis");
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rtb = f < 0.0 ? (dx=x2-x1,x1) : (dx=x1-x2,x2);
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for (j=0;j<JMAX;j++) {
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fmid=func(xmid=rtb+(dx *= 0.5));
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if (fmid <= 0.0) rtb=xmid;
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if (fabs(dx) < xacc || fmid == 0.0) return rtb;
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}
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nrerror("Too many bisections in rtbis");
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return 0.0;
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}
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