"Liam E. Gumley" wrote: > I run IDL 5.3 on SGI IRIX 6.4, so the compile went as follows: > > % f77 -n32 -KPIC -u -fullwarn -c vecadd.f > % ld -n32 -o vecadd.so vecadd.o For compiler flags on other UNIX platforms, see $IDL_DIR/external/call_external/Fortran/Makefile Cheers, Liam.