30 lines
521 B
C
30 lines
521 B
C
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#include <math.h>
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#include "nrutil.h"
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#define BIG 1.0e30
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extern int nn;
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extern float *xx,*yy,*sx,*sy,*ww,aa,offs;
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float chixy(bang)
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float bang;
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{
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int j;
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float ans,avex=0.0,avey=0.0,sumw=0.0,b;
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b=tan(bang);
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for (j=1;j<=nn;j++) {
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ww[j] = SQR(b*sx[j])+SQR(sy[j]);
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sumw += (ww[j] = (ww[j] < 1.0/BIG ? BIG : 1.0/ww[j]));
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avex += ww[j]*xx[j];
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avey += ww[j]*yy[j];
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}
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avex /= sumw;
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avey /= sumw;
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aa=avey-b*avex;
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for (ans = -offs,j=1;j<=nn;j++)
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ans += ww[j]*SQR(yy[j]-aa-b*xx[j]);
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return ans;
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}
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#undef BIG
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