28 lines
446 B
C++
28 lines
446 B
C++
#include "nr.h"
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DP NR::midpnt(DP func(const DP), const DP a, const DP b, const int n)
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{
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int it,j;
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DP x,tnm,sum,del,ddel;
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static DP s;
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if (n == 1) {
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return (s=(b-a)*func(0.5*(a+b)));
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} else {
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for(it=1,j=1;j<n-1;j++) it *= 3;
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tnm=it;
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del=(b-a)/(3.0*tnm);
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ddel=del+del;
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x=a+0.5*del;
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sum=0.0;
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for (j=0;j<it;j++) {
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sum += func(x);
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x += ddel;
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sum += func(x);
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x += del;
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}
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s=(s+(b-a)*sum/tnm)/3.0;
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return s;
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}
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}
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