24 lines
471 B
C++
24 lines
471 B
C++
#include <cmath>
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#include "nr.h"
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using namespace std;
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DP NR::rtnewt(void funcd(const DP, DP &, DP &), const DP x1, const DP x2,
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const DP xacc)
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{
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const int JMAX=20;
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int j;
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DP df,dx,f,rtn;
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rtn=0.5*(x1+x2);
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for (j=0;j<JMAX;j++) {
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funcd(rtn,f,df);
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dx=f/df;
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rtn -= dx;
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if ((x1-rtn)*(rtn-x2) < 0.0)
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nrerror("Jumped out of brackets in rtnewt");
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if (fabs(dx) < xacc) return rtn;
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}
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nrerror("Maximum number of iterations exceeded in rtnewt");
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return 0.0;
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}
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