[bananas]GNU 3.2.2 compiler fails!

[Eric Greisen]

The GNU 3.2.2 gcc compiler appears to get some AIPS subroutines wrong
when optimizing at the usual levels.  The application of bandpass
calibration failed as did the DO3D option in IMAGR.  These are
non-trivial applications - not caught by the Y2K or DDT tests.  I
suppose that we could identify the subroutines involved.  One seems to
be IOBSRC which zeros 2 parameters in common following the
integer(2,3) arrays it is designed to set for BP cal.  The other has
to do with rotating u,v,w to u',v',w' and back.  But there are
certainly more routines than these and both of these should be
optimized since they are used a lot.

This compiler comes in two flavors - that shipped with RedHat 9 which
identifies itself with RedHat on a /usr/bin/g77 -v and that taken
directly from GNU's web sites.  The two appear to differ in their
affects on IMAGR but neither is correct; they both blast calibration
apparently in similar ways.

GNU 3.3 does not appear to have this problem.  We recommend that users
of RedHat 7.3 and lower systems continue to use the GNU 2.95.3
compiler. More recent systems will need to use 3.3 - but even there we
urge caution.  We know of no problems but....

I will now update the aips web site to issue this warning.  In time, I
expect that we will make the gnu 3.3 tarball available from that site
as we already do for the 2.95.3 version.

I had hoped that we could start back to using the compiler shipped
with RedHat.  Unfortunately, that does not seem to be the case.

Eric Greisen