Re: how to use gsl with the guile ffi

[tantalum]

only thing is, im not sure yet what i would set LD_LIBRARY_PATH to, as the 
following are all the library files gsl installs:

gsl /usr/lib/libgsl.so
gsl /usr/lib/libgsl.so.23
gsl /usr/lib/libgsl.so.23.1.0
gsl /usr/lib/libgslcblas.so
gsl /usr/lib/libgslcblas.so.0
gsl /usr/lib/libgslcblas.so.0.0.0

ldd output is
  ldd /usr/lib/libgsl.so
        linux-vdso.so.1 (0x00007ffeb5ded000)
        libm.so.6 => /usr/lib/libm.so.6 (0x00007f804bc32000)
        libc.so.6 => /usr/lib/libc.so.6 (0x00007f804ba6e000)
        /usr/lib64/ld-linux-x86-64.so.2 (0x00007f804c282000)

something that works in my c test program is preloading libgslcblas with 
RTLD_GLOBAL.

  void* a = dlopen("/usr/lib/libgslcblas.so", RTLD_NOW | RTLD_GLOBAL);
  void* b = dlopen("/usr/lib/libgsl.so", RTLD_NOW);

but guile uses libtool of course. as far as i understand it, libgslcblas is a 
cblas implementation that can be replaced with other ones, and that is why it 
is separate.

the RTLD_GLOBAL feature has been referenced in a mailing list post from 2012 "Re: 
using GSL with cblas via FFI"
https://lists.gnu.org/archive/html/guile-user/2012-06/msg00008.html
https://lists.gnu.org/archive/html/guile-user/2011-03/msg00071.html

what might eventually work is to compile gsl myself with the dependency 
excluded or statically linked. or using a c extension instead of the ffi.
but it is interesting also how the example from the manual does not work and gives the 
same error message. (define libm (dynamic-link "libm"))  
https://www.gnu.org/software/guile/manual/html_node/Dynamic-FFI.html

it would be interesting to know if it works for others.