Re: Problems with creating executables using GSL with RadHat Linux

[Jon McAuliffe <jon at vindigo dot com>]

this may sound silly, but try putting the gcc arguments on the
command line like this

  gcc -L/usr/local/lib/gsl main.o -lgslroots

because (quoting from the man page)

For the link  stage,  all .o  files  corresponding  to  source
files, -l libraries, unrecognized filenames (including named
.o  object  files and  .a archives) are passed to the linker
in command-line order.

which means that if you put main.o last on the command line,
none of its references to functions in libgslroots.a will
get resolved.

cheers
jon.



Mihajlo wrote:
> 
> Hello,
> 
> I wanted to try out GSL for some numerical equation solvers, but I am
> running into problems generating an executable for even a simple example
> code as given in
> http://sourceware.cygnus.com/gsl/ref/gsl-ref_9.html#SEC88.  The
> installation seamed to have gone fine, the 'make check' script returned
> almost all tests passed except for the last portion (attached is a copy
> of the make_check.log file).  However when I try to build an example
> executable I get into problems.  Executing
> 
>     gcc -I/usr/local/include/gsl -c main.c
> 
>  seams to go fine, but when I do
> 
>       gcc -lgslroots -L/usr/local/lib/gsl main.o
> 
> I get the following errors:
> 
> [root@ash CS690]# gcc -lgslroots -L/usr/local/lib/gsl main.o
> main.o: In function `main':
> main.o(.text+0xf0): undefined reference to `sqrt'
> main.o(.text+0x148): undefined reference to `gsl_root_fsolver_brent'
> main.o(.text+0x14e): undefined reference to `gsl_root_fsolver_alloc'
> main.o(.text+0x15f): undefined reference to `gsl_root_fsolver_name'
> main.o(.text+0x1ae): undefined reference to `gsl_root_fsolver_iterate'
> main.o(.text+0x1bf): undefined reference to `gsl_root_fsolver_root'
> main.o(.text+0x1d2): undefined reference to `gsl_root_fsolver_interval'
> main.o(.text+0x1f8): undefined reference to `gsl_root_test_interval'
> collect2: ld returned 1 exit status
> 
> ,even though the library file libgslroots.a seams to be loaded.  I also
> did a 'grep' for some of the listed references and they are indeed
> present in the libgslroots.a file.
> 
> I am attaching all three example files that I am trying to compile.
> What could be the problem?!
> 
> Thanks for your help.
> 
>                                                   ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> 
> double quadratic (double x, void *params)
> {
>   struct quadratic_params *p = (struct quadratic_params *) params;
> 
>   double a = p->a;
>   double b = p->b;
>   double c = p->c;
> 
>   return (a * x + b) * x + c;
> }
> 
> double quadratic_deriv (double x, void *params)
> {
>   struct quadratic_params *p = (struct quadratic_params *) params;
> 
>   double a = p->a;
>   double b = p->b;
>   double c = p->c;
> 
>   return 2.0 * a * x + b;
> }
> 
> void
> quadratic_fdf (double x, void *params, double *y, double *dy)
> {
>   struct quadratic_params *p = (struct quadratic_params *) params;
> 
>   double a = p->a;
>   double b = p->b;
>   double c = p->c;
> 
>   *y = (a * x + b) * x + c;
>   *dy = 2.0 * a * x + b;
> }
> 
>                                                   ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> struct quadratic_params {double a, b, c;};
> double quadratic (double x, void *params);
> double quadratic_deriv (double x, void *params);
> void quadratic_fdf (double x, void *params, double *y, double *dy);
> 
>                                                   ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> #include <stdio.h>
> #include <gsl_errno.h>
> #include <gsl_math.h>
> #include <gsl_roots.h>
> 
> #include "demof.h"
> #include "demof.c"
> 
> int
> main ()
> {
>   int status;
>   int iterations = 0, max_iterations = 100;
>   gsl_root_fsolver *s;
>   double r = 0, r_expected = sqrt (5.0);
>   gsl_interval x = {0.0, 5.0};
>   gsl_function F;
>   struct quadratic_params params = {1.0, 0.0, -5.0};
> 
>   F.function = &quadratic;
>   F.params = &params;
> 
>   s = gsl_root_fsolver_alloc (gsl_root_fsolver_brent, &F, x);
> 
>   printf ("using %s method\n", gsl_root_fsolver_name (s));
> 
>   printf ("%5s [%9s, %9s] %9s %9s %10s %9s\n",
>           "iter", "lower", "upper", "root", "actual", "err", "err(est)");
> 
>   do
>     {
>       iterations++;
>       status = gsl_root_fsolver_iterate (s);
>       r = gsl_root_fsolver_root (s);
>       x = gsl_root_fsolver_interval (s);
>       status = gsl_root_test_interval (x, 0, 0.001);
> 
>       if (status == GSL_SUCCESS)
>         printf ("Converged:\n");
> 
>       printf ("%5d [%.7f, %.7f] %.7f %.7f %+.7f %.7f\n",
>               iterations, x.lower, x.upper,
>               r, r_expected, r - r_expected, x.upper - x.lower);
>     }
>   while (status == GSL_CONTINUE && iterations < max_iterations);
> 
> }