Date: Sun, 13 Nov 1994 19:32:31 -0500 (CDT)
From: Aaron Ucko <UCKO AT VAX1 DOT ROCKHURST DOT EDU>
Subject: Paranoia
To: djgpp AT sun DOT soe DOT clarkson DOT edu
Organization: Rockhurst College; Kansas City, MO

As previously recommended, I tried running Paranoia with DJGPP (and a few
other DOS products...):

DJGPP (no optimization, double precision):  Certain basic operations
(multiplication, etc.) neither truncate nor round correctly [actually, this
occurs in _all_ the double-precision cases I could test].  Crashes with
untrapped floating point exception when calculating Z^i for small values of Z
and i.

DJGPP (optimization):  Gets _very_ confused.  First thinks base is 4096 (!),
then 0.  Dies because 1 - 1/2 - (base) >= 1/2.

DJGPP(no opt., single prec):  Crashes on computing Z^i.

TC++ 1.01 (double)  truncation/rounding problem; dividing by 0 yields
(trapped) exceptions.  Displays message about arguments to pow() being out
of its domain, but doesn't tell Paranoia.  Double precision thing only
problem.

TC++ 1.01 (single) pow() message only--rated perfect (!)

QBasic 6.20 [no flames, please--I just wanted to see what would happen]
Choked on "next" being conditional--had to be kluged around.  Complained
about various semi-trapped overflows.

QB (double) trunc/round problem; overflow problems [Overflowed to max
_single_-precision # (!)]

I have not yet tested with QC or QP, as I don't have them installed right
now.  The general conclusion, though, seems to be that the 8087/287/387/486+
does _not_ round correctly in double-precision mode.

--- Aaron Ucko (ucko AT vax1 DOT rockhurst DOT edu; finger for PGP public key) -=- httyp!
-=*=-Just because you're paranoid doesn't mean they aren't out to get you.-=*=-
Geek code 2.1 [finger hayden AT vax1 DOT mankato DOT msus DOT edu for explanation]: 
 GCS/M/S d(-) H s g+ p? !au a-- w+ v+ C++(+++)>++++ U-(S+)>++++ P+ L>++ 3(-) 
 E-(----) !N>++ K- W(--) M-(--) V(--) po-(--) Y+(++) t(+) !5 j R G tv--(-) 
 b+++ !D(--) B--(---) e>++++(*) u++(@) h!() f(+) r-(--)>+++ n+(-) y?