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29 lines
516 B
C
29 lines
516 B
C
#define FUNC(x) ((*funk)(1.0/(x))/((x)*(x)))
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double midinf(double (*funk)(double), double aa, double bb, int n)
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{
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double x,tnm,sum,del,ddel,b,a;
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static double s;
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int it,j;
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b=1.0/aa;
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a=1.0/bb;
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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=1;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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return (s=(s+(b-a)*sum/tnm)/3.0);
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}
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}
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#undef FUNC
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