Singular

Is it possible to call Singular from C/C++?

As Singular is a C++ program, it is possible.
On the other side, Singular was not designed as library
- it requires its own memory manager (which may interfere with others),
it requires that its initialization is run (which is in main() and not
in seperate routines).
To sum it up: yes, it is possible, but requires quite a lot of work.

Now, after 3 years, have something changed?

It is not Singulars main goal to create a C++ library,
but, yes, it is possible, and some programs use Singular as a C++ library.

Once you have build a stand alone Singular, the Makefile in ./Singular
provides the targets libsingular.a and libsingular.so
which contain all Singular functions. (The problems with coexisting
memory managers have been solved).
Rudimentary documentation of the internals can be found at
http://www.mathematik.uni-kl.de/ftp/pub ... natomy.tgz