54 lines
988 B
C
54 lines
988 B
C
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/* Driver for routine dbrent */
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#include <stdio.h>
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#include <math.h>
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#define NRANSI
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#include "nr.h"
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#define TOL 1.0e-6
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#define EQL 1.0e-4
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float dfunc(float x)
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{
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return -bessj1(x);
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}
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float func(float x)
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{
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return bessj0(x);
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}
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int main(void)
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{
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int i,iflag,j,nmin=0;
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float ax,bx,cx,fa,fb,fc,xmin,dbr,amin[21];
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printf("\nMinima of the function bessj0\n");
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printf("%10s %8s %16s %12s %11s\n",
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"min. #","x","bessj0(x)","bessj1(x)","DBRENT");
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for (i=1;i<=100;i++) {
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ax=i;
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bx=i+1.0;
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mnbrak(&ax,&bx,&cx,&fa,&fb,&fc,func);
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dbr=dbrent(ax,bx,cx,func,dfunc,TOL,&xmin);
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if (nmin == 0) {
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amin[1]=xmin;
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nmin=1;
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printf("%7d %15.6f %12.6f %12.6f %12.6f\n",
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nmin,xmin,func(xmin),dfunc(xmin),dbr);
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} else {
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iflag=0;
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for (j=1;j<=nmin;j++)
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if (fabs(xmin-amin[j]) <= EQL*xmin) iflag=1;
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if (iflag == 0) {
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amin[++nmin]=xmin;
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printf("%7d %15.6f %12.6f %12.6f %12.6f\n",
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nmin,xmin,func(xmin),dfunc(xmin),dbr);
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}
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}
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}
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return 0;
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}
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#undef NRANSI
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