Singular

Thanks for your help. Indeed, doing this did the trick:

[code]export SINGULAR_BASE=/home/mydir/Sources-spielwiese/
export SINGULAR_LIB_DIR=$SINGULAR_BASE/Singular/.libs/
export SINGULAR_LIB_2=$SINGULAR_BASE/libpolys/polys/.libs/
export SINGULAR_LIB_3=$SINGULAR_BASE/resources/.libs/
export SINGULAR_LIB_4=$SINGULAR_BASE/omalloc/.libs/

export SINGULAR_LIB_5=$SINGULAR_BASE/libpolys/polys/.libs/p_Procs_FieldIndep.so

export SINGULAR_PROCS_DIR=$SINGULAR_BASE/Singular/MOD/
export SINGULARPATH=$SINGULAR_BASE/Singular/LIB/

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$SINGULAR_LIB_DIR:$SINGULAR_LIB_2:$SINGULAR_LIB_3:$SINGULAR_LIB_4:$SINGULAR_LIB_5:$SINGULARPATH:$SINGULAR_PROCS_DIR[/code]

These are 2 different things:

A) shared libraries: the rules for your OS apply: i.e. set LD_LIBRARY_PATH for the dynamic linker to find then
(see "man ld", "man ldconfig", "info gcc").
They are called lib*.so and can be found (on Linux) by "ldd libSingular.so"

B) dynamic modules for Singular: their name does not start with lib, and they are searched in the places given by SINGULAR_PROCS_DIR (and ...., see my previous post)

From where my own code is located, the Singular directory is 2 directories up.
So I make this call in my code:
[quote]
siInit((char *)"../../Singular/.libs/libSingular.so");
[/quote]
Next, I do an export, as you suggested, for the following directories:
[quote]
export SINGULAR_PROCS_DIR=../../Singular/MOD/
export SINGULARPATH=../../Singular/LIB/
[/quote]
Now, when running my code it complains:
[quote]
./mysingular: error while loading shared libraries: libSingular-4.1.0.so: cannot open shared object file: No such file or directory
[/quote]
The only "libSingular-4.1.0.so" I can find is this one:
[quote]
../../Singular/.libs/libSingular-4.1.0.so
[/quote]
Do I have to link this to the "MOD" directory?

First of all: siInit must only be called once.

Its arguments should be a readable file (usually it is the main binary Singular,
derived from argv[0]).
If the directory this file is in is %b, and %r is the prefix given in the configuration (or /usr/local
if nothing was given)
then Singulars *.lib files are searched in %b/../share/singular/LIB, and %b/LIB,
dynamic modules are searched in "%b/MOD;" "%r/lib/singular/MOD;" "%r/libexec/singular/MOD;".
(see ressources/feRessources.cc).
Otherwise, one may set the environment variables
SINGULAR_PROCS_DIR for the dynamic modules,
SINGULARPATH for *.lib files,

Adding
[quote]siInit((char *)"./Singular/libsingular.so");[/quote]
still gives me:
[quote]
? cannot open `standard.lib`
// ** Could not find dynamic library: p_Procs_FieldIndep.so (path )
// ** Singular will work properly, but much slower.
// ** See the INSTALL section in the Singular manual for details.
[/quote]
Adding both lines like:
[quote]
siInit((char *)"../../Singular/.libs/libSingular.so");
siInit((char *)"../../libpolys/polys/.libs/p_Procs_FieldIndep.so");
[/quote]
gives me:
[quote] ? cannot open `standard.lib`
coeff 7 already initialized
coeff 8 already initialized
? cannot open `standard.lib`
// ** Could not find dynamic library: p_Procs_FieldIndep.so (path )
// ** Singular will work properly, but much slower.[/quote]

You are missing the initialization:
[code]
void main()
{
// init path names etc.: the string should point to an existing
// executable in a directory $B
// LIBs are searched in $B/LIB, $B/../LIB,
// see kernel/feRessource.cc
// also needed to find its dynamic modules in $B/MOD, $B/../lib/singular/MOD, $B/../libexec/singular/MOD,...
siInit((char *)"./Singular/libsingular.so");
....
[/code]

I downloaded the source code for Singular from https://github.com/Singular/Sources and compiled it succesfully.
Now I want to create my own code and link it to the Singular libs.
My (very simple) code is:
[code]
#include <libsingular.h>
int main()
{
char** n = (char**) omalloc( 3*sizeof(char*) );
n[0]=omStrDup("x");
n[1]=omStrDup("y");
n[2]=omStrDup("z");
ring R = rDefault(0, 3, n);
}[/code]
I compile this with:
[quote]
SINGULAR_BASE=/home/mkolstein/Singular/Sources-spielwiese/
FOO=$SINGULAR_BASE/libpolys/polys/.libs/p_Procs_FieldIndep.so
g++ -I$SINGULAR_BASE/Singular/ -I$SINGULAR_BASE/ -I$SINGULAR_BASE/libpolys/ -I$SINGULAR_BASE/factory/include/ -I$SINGULAR_BASE/libpolys/polys/.libs/ -o mysingular mySingular.cxx -L$SINGULAR_BASE/Singular/.libs/ -lSingular -L$SINGULAR_BASE/libpolys/polys/.libs/ -lpolys $FOO -L$SINGULAR_BASE/resources/.libs/ -lsingular_resources -L$SINGULAR_BASE/omalloc/.libs/ -lomalloc
[/quote]
and before running my executable, also make sure LD_LIBRARY_PATH can find all ".so" files:
[quote]
export SINGULAR_BASE=/home/mkolstein/Singular/Sources-spielwiese/
export SINGULAR_LIB_DIR=$SINGULAR_BASE/Singular/.libs/
export SINGULAR_LIB_2=$SINGULAR_BASE/libpolys/polys/.libs/
export SINGULAR_LIB_3=$SINGULAR_BASE/resources/.libs/
export SINGULAR_LIB_4=$SINGULAR_BASE/omalloc/.libs/
export SINGULAR_LIB_5=$SINGULAR_BASE/libpolys/polys/.libs/p_Procs_FieldIndep.so
export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:$SINGULAR_LIB_DIR:$SINGULAR_LIB_2:$SINGULAR_LIB_3:$SINGULAR_LIB_4:$SINGULAR_LIB_5
[/quote]
However, when I run my executable "mysingular", I get the following warning:
[quote]
Bug >>feArgv0 == NULL<< at feResource.cc:403
// ** Could not find dynamic library: p_Procs_FieldIndep.so (path )
// ** Singular will work properly, but much slower.
// ** See the INSTALL section in the Singular manual for details.
[/quote]
How can I avoid this?