[fa.info-vax] Math lib bombing under V4.2

MRL%PFCVAX@MIT-MC.ARPA (09/08/85)

	Concerning the math lib problems people are complaining about under
V4.2, we also had the same problem here.  A program that worked fine under V4.1
bombed in a math lib routine (exponential) under V4.2 .  I recompiled using
/CHECK=ALL, and found there were several cases of floating point underflows and
one case of array out of bounds.  The code was not affected by the fact that
a variable was zero rather than a very small number, and this could be the case
for many programs.  Also, obviously the array out of bounds was not affecting
memory that was used later in the program.  However, the new math lib routine
must be more susceptible to one of these problems.  ( By the fact that several
people are reporting this problem, I would suspect it is being caused by the
floating point underflow, as I can't believe that THAT many people have coded
their routines incorrectly so that their array are running out of bounds,
particularly because that problem usually will cause immediate bad results. )

	By the way, when we upgraded to 4.2, we lost our primary swap file
somehow, although our primary page file was ok.  I have no idea what caused
this!  Somehow the system was able to be booted to the point where it could
install the secondary swap file (which is on a different disk).  Besides this,
we had no major problems, except a CPU board died while it was trying to
reboot after PHASE 4 (luckily not during the middle of a crucial stage!!)
We did the upgrade with a minimum startup, although the documentation gives
no warnings about the fact that you may need to manually configure the devices
(i.e. tape drive) that is to be used during the upgrade.

							---   Mark