32 lines
816 B
C
32 lines
816 B
C
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#define NRANSI
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#include "nrutil.h"
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void bcuint(float y[], float y1[], float y2[], float y12[], float x1l,
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float x1u, float x2l, float x2u, float x1, float x2, float *ansy,
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float *ansy1, float *ansy2)
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{
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void bcucof(float y[], float y1[], float y2[], float y12[], float d1,
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float d2, float **c);
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int i;
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float t,u,d1,d2,**c;
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c=matrix(1,4,1,4);
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d1=x1u-x1l;
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d2=x2u-x2l;
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bcucof(y,y1,y2,y12,d1,d2,c);
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if (x1u == x1l || x2u == x2l) nrerror("Bad input in routine bcuint");
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t=(x1-x1l)/d1;
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u=(x2-x2l)/d2;
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*ansy=(*ansy2)=(*ansy1)=0.0;
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for (i=4;i>=1;i--) {
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*ansy=t*(*ansy)+((c[i][4]*u+c[i][3])*u+c[i][2])*u+c[i][1];
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*ansy2=t*(*ansy2)+(3.0*c[i][4]*u+2.0*c[i][3])*u+c[i][2];
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*ansy1=u*(*ansy1)+(3.0*c[4][i]*t+2.0*c[3][i])*t+c[2][i];
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}
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*ansy1 /= d1;
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*ansy2 /= d2;
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free_matrix(c,1,4,1,4);
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}
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#undef NRANSI
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