linkimage query

[src <src(at)ungoliant.ulo.ucl.ac.uk>]

hi,
I realise many people don't use Linkimage, but maybe someone might know
what's happening here.  Basically I've written some code that links to IDL
with LinkImage, it seems to work fine in most circumstances, but the fact
I've a problem in one case makes me wonder if I've just been lucky in all
the other cases.

The code is used on two platforms, gcc/Linux/x86 and cc/DEC
unix/alpha.  What compiler flags should be used when compiling a binary to
be used with linkimage?  I've been using:

-shared                  for gcc
-std -shared             for cc

Are these o.k. or should different flags be used?  The problem I mentioned
above is a segmentation fault that occurs with only one of the alpha boxes
I use (I think it might have a different version of the alpha chip, but
the binary should work on all alphas).  The reason I asked about the
compiler flags is that cc produces the following warning but gcc doesn't:

ld:
Warning: Unresolved:
sqrt
IDL_VarEnsureSimple
IDL_Message
exp
log

...etc, even thought I've #include <math.h> and export.h.

any info would be much appreciated,
Rich