56 lines
1.2 KiB
C
56 lines
1.2 KiB
C
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/* Driver for routine dfpmin */
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#include <stdio.h>
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#define NRANSI
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#include "nr.h"
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#include "nrutil.h"
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static int nfunc,ndfunc;
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float func(float x[])
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{
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float x1p2sqr=SQR(2.0+x[1]);
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nfunc++;
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return 10.0*
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SQR(SQR(x[2])*(3.0-x[1])-SQR(x[1])*(3.0+x[1]))+
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x1p2sqr/(1.0+x1p2sqr);
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}
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void dfunc(float x[],float df[])
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{
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float x1sqr=SQR(x[1]),x2sqr=SQR(x[2]),x1p2=x[1]+2.0;
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float x1p2sqr=SQR(x1p2);
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ndfunc++;
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df[1]=20.0*(x2sqr*(3.0-x[1])-x1sqr*(3.0+x[1]))*(-x2sqr-6.0*x[1]-3.0*x1sqr)+
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2.0*x1p2/(1.0+x1p2sqr)-2.0*x1p2*x1p2sqr/SQR((1.0+x1p2sqr));
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df[2]=40.0*(x2sqr*(3.0-x[1])-x1sqr*(3.0+x[1]))*x[2]*(3.0-x[1]);
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}
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#define NDIM 2
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#define GTOL 1.0e-4
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int main(void)
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{
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int iter;
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float *p,fret;
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p=vector(1,NDIM);
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printf("True minimum is at (-2.0,+-0.89442719)\n");
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nfunc=ndfunc=0;
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p[1]=0.1;
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p[2]=4.2;
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printf("Starting vector: (%7.4f,%7.4f)\n",p[1],p[2]);
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dfpmin(p,NDIM,GTOL,&iter,&fret,func,dfunc);
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printf("Iterations: %3d\n",iter);
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printf("Func. evals: %3d\n",nfunc);
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printf("Deriv. evals: %3d\n",ndfunc);
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printf("Solution vector: (%9.6f,%9.6f)\n",p[1],p[2]);
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printf("Func. value at solution %14.6g\n",fret);
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free_vector(p,1,NDIM);
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return 0;
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}
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#undef NRANSI
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