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#define powell1_N 4
#define powell1_P 4
#define powell1_NTRIES 4
static double powell1_x0[powell1_P] = { 3.0, -1.0, 0.0, 1.0 };
static double powell1_epsrel = 1.0e-5;
static void
powell1_checksol(const double x[], const double sumsq,
const double epsrel, const char *sname,
const char *pname)
{
size_t i;
const double sumsq_exact = 0.0;
gsl_test_rel(sumsq, sumsq_exact, epsrel, "%s/%s sumsq",
sname, pname);
for (i = 0; i < powell1_P; ++i)
{
gsl_test_rel(x[i], 0.0, epsrel, "%s/%s i=%zu",
sname, pname, i);
}
}
static int
powell1_f (const gsl_vector * x, void *params, gsl_vector * f)
{
double x1 = gsl_vector_get (x, 0);
double x2 = gsl_vector_get (x, 1);
double x3 = gsl_vector_get (x, 2);
double x4 = gsl_vector_get (x, 3);
gsl_vector_set(f, 0, x1 + 10.0*x2);
gsl_vector_set(f, 1, sqrt(5.0) * (x3 - x4));
gsl_vector_set(f, 2, pow(x2 - 2.0*x3, 2.0));
gsl_vector_set(f, 3, sqrt(10.0) * pow((x1 - x4), 2.0));
return GSL_SUCCESS;
}
static int
powell1_df (const gsl_vector * x, void *params, gsl_matrix * J)
{
double x1 = gsl_vector_get (x, 0);
double x2 = gsl_vector_get (x, 1);
double x3 = gsl_vector_get (x, 2);
double x4 = gsl_vector_get (x, 3);
double term1 = x2 - 2.0*x3;
double term2 = x1 - x4;
gsl_matrix_set(J, 0, 0, 1.0);
gsl_matrix_set(J, 0, 1, 10.0);
gsl_matrix_set(J, 0, 2, 0.0);
gsl_matrix_set(J, 0, 3, 0.0);
gsl_matrix_set(J, 1, 0, 0.0);
gsl_matrix_set(J, 1, 1, 0.0);
gsl_matrix_set(J, 1, 2, sqrt(5.0));
gsl_matrix_set(J, 1, 3, -sqrt(5.0));
gsl_matrix_set(J, 2, 0, 0.0);
gsl_matrix_set(J, 2, 1, 2.0*term1);
gsl_matrix_set(J, 2, 2, -4.0*term1);
gsl_matrix_set(J, 2, 3, 0.0);
gsl_matrix_set(J, 3, 0, 2.0*sqrt(10.0)*term2);
gsl_matrix_set(J, 3, 1, 0.0);
gsl_matrix_set(J, 3, 2, 0.0);
gsl_matrix_set(J, 3, 3, -2.0*sqrt(10.0)*term2);
return GSL_SUCCESS;
}
static gsl_multifit_function_fdf powell1_func =
{
&powell1_f,
&powell1_df,
NULL,
powell1_N,
powell1_P,
NULL,
0,
0
};
static test_fdf_problem powell1_problem =
{
"powell_singular",
powell1_x0,
NULL,
&powell1_epsrel,
powell1_NTRIES,
&powell1_checksol,
&powell1_func
};
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