External SQL functions exported by DLLs

[Peter Sullvan]

We have a few rather advanced calculation routines
developed in C++. Currently we are using a Sybase ASA
database for our app. and these routines are accessible
by so called external functions exported by a DLL
(dynamic link library) that we wrote in C++. Sybase
supports this quite nicely.

The client app can call such routines by:

"select get_roof_angle() as angle from dummy;"
or
":angle = call get_roof_angle();"

Now we are checking if other databases can provide us
with similar abilities. So I just wonder if PostgreSQL
supports the ability to call a routine exported by a
DLL? If yes, does anyone know the SQL syntax to declare
it in PostgreSQL.

Best regards
Peter Sullvan