Hi,
I was trying to perform extrapolation using the function "
gsl_interp2d_eval_extrap_e ( ) " mentioned in gsl-ref.pdf and found that the
real name of the function is something else. Below is the result of compiling
the attached example file named bug_in_interp2d.c. I am not sure if the
following has been already reported.
============================================================
bug_in_interp2d.o: In function `main':
bug_in_interp2d.c:(.text+0x3fc): undefined reference to
`gsl_interp2d_eval_extrap_e'
collect2: error: ld returned 1 exit status
============================================================
I was actually looking for "gsl_interp1d_eval_extrap ( )" in the current
release gsl-2.5. But ended with a bug reporting from 2D-interpolation stuffs.
With kind regards,
Brijesh Upadhaya
-----------------------------
Doctoral Student
Department of Electrical Engineering and Automation
School of Electrical Engineering, Aalto University
P. O. Box 15500, FI-00076 AALTO,
FINLAND
/* bug_in_interp2d.c
*
* 29.6.2018 Brijesh Upadhaya
*
* Test for bug
* Typo mistake at line 97 in file gsl-2.5/interpolation/gsl_interp2d.h)
*
* Missing function "int gsl_interp2d_eval_extrap_e ()"
* The function "int gsl_interp2d_eval_extrap_e ()" is mentioned in gsl-ref.pdf
*
* However the actual function name is "int gsl_interp2d_eval_e_extrap ()"
*/
#include <stdio.h>
#include <stdlib.h>
#include <gsl/gsl_math.h>
#include <gsl/gsl_interp2d.h>
int
main (void)
{
const gsl_interp2d_type *T = gsl_interp2d_bilinear;
const size_t N = 100;
const double xa[] = { 0.0, 1.0 };
const double ya[] = { 0.0, 1.0 };
const size_t nx = sizeof (xa) / sizeof (double);
const size_t ny = sizeof (ya) / sizeof (double);
double *za = (double *) malloc (nx * ny * sizeof (double));
gsl_interp_accel *xacc = gsl_interp_accel_alloc ();
gsl_interp_accel *yacc = gsl_interp_accel_alloc ();
gsl_interp2d *sp = gsl_interp2d_alloc (T, nx, ny);
gsl_interp2d_set (sp, za, 0, 0, 0.0);
gsl_interp2d_set (sp, za, 1, 0, 1.0);
gsl_interp2d_set (sp, za, 0, 1, 1.0);
gsl_interp2d_set (sp, za, 1, 1, 0.5);
gsl_interp2d_init (sp, xa, ya, za, nx, ny);
size_t i, j;
for (i = 0; i < N; ++i)
{
double xi = (double) i / ((double) N - 1.0);
for (j = 0; j < N; ++j)
{
double yi = (double) j / ((double) N - 1.0);
double zi = gsl_interp2d_eval (sp, xa, ya, za, xi, yi, xacc, yacc);
fprintf (stdout, "%f %f %f\n", xi, yi, zi);
}
fprintf (stdout, "\n");
}
double ze = gsl_interp2d_eval_extrap (sp, xa, ya, za, 1.05, 1.05, xacc, yacc);
/* One of the following function is defined in gsl-ref.pdf */
double ze0 = 0.0;
int c = gsl_interp2d_eval_extrap_e (sp, xa, ya, za, 1.05, 1.05, xacc, yacc, &ze0);
//int c = gsl_interp2d_eval_e_extrap (sp, xa, ya, za, 1.05, 1.05, xacc, yacc, &ze0);
(void) c;
fprintf (stderr, "%f %f\n", ze, ze0);
gsl_interp2d_free (sp);
gsl_interp_accel_free (yacc);
gsl_interp_accel_free (xacc);
free (za);
return 0;
}
