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/* driver for hybrd1 example. */
#include <stdio.h>
#include <math.h>
#include <minpack.h>
void fcn(int *n, double *x, double *fvec, int *iflag);
int main()
{
int j, n, info, lwa;
double tol, fnorm;
double x[9], fvec[9], wa[180];
int one=1;
n = 9;
/* the following starting values provide a rough solution. */
for (j=1; j<=9; j++)
{
x[j-1] = -1.;
}
lwa = 180;
/* set tol to the square root of the machine precision. */
/* unless high solutions are required, */
/* this is the recommended setting. */
tol = sqrt(dpmpar_(&one));
hybrd1_(&fcn, &n, x, fvec, &tol, &info, wa, &lwa);
fnorm = enorm_(&n, fvec);
printf(" final L2 norm of the residuals %15.7g\n", fnorm);
printf(" exit parameter %10i\n", info);
printf(" final approximate solution\n");
for (j=1; j<=n; j++) printf("%s%15.7g",j%3==1?"\n ":"", x[j-1]);
printf("\n");
return 0;
}
void fcn(int *n, double *x, double *fvec, int *iflag)
{
/* subroutine fcn for hybrd1 example. */
int k;
double one=1, temp, temp1, temp2, three=3, two=2, zero=0;
for (k=1; k <= *n; k++)
{
temp = (three - two*x[k-1])*x[k-1];
temp1 = zero;
if (k != 1) temp1 = x[k-1-1];
temp2 = zero;
if (k != *n) temp2 = x[k+1-1];
fvec[k-1] = temp - temp1 - two*temp2 + one;
}
return;
}
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