tiberio@seismo.UUCP (Mike Tiberio) (08/08/84)
a program, run on a sun and on a 780, both with 4.2 BSD:
main()
{
double log10();
printf("%f\n", log10(0.));
}
sun responds:
Infinity
vax responds:
-73891372717101319000000000000000000000.000000
may the joker responsible for the answer found on the sun be shot!
seismo!tiberiobrian@uwvax.ARPA (08/09/84)
I don't know if I would go so far as to shoot the "joker". At least he
made an attempt at giving the right answer, even though he was wrong. The
vax answer, however, can't even be construed as an attempt at the correct
answer, it's ludicrous and WRONG. Anyway, what little I remember from high
school calculus tells me that log10(0) is UNDEFINED, not Infinity. This
is because ten to any power does not equal zero. Cheers to the Sun programmer
who had the idea... I love it.
--
Brian Pinkerton @ wisconsin
...!{allegra,heurikon,ihnp4,seismo,sfwin,ucbvax,uwm-evax}!uwvax!brian
brian@wisc-rsch.arpachris@umcp-cs.UUCP (08/10/84)
Actually, it makes sense that the sun would say ``Infinity'':
log10(0.0) returns the largest (smallest?) possible machine value and
sets errno to EDOM.
--
In-Real-Life: Chris Torek, Univ of MD Comp Sci (301) 454-7690
UUCP: {seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet: chris@umcp-cs ARPA: chris@marylandwb@gamma.UUCP (Bill Beblo) (08/26/84)
My experience with the Sun 2 workstation is that it returns a value which is printed via printf as "NAN" (not a number). I was under the impression this had something to do with the IEEE standard for floating point software. They claim they conform. My question is whether or not they are consistent when using their Sky hardware FP processor. Bill Beblo Bell Communications Research 600 Mountain Avenue Murray Hill, New Jersey 07974 (201) 582-7365
sunny@sun.uucp (Sunny Kirsten) (08/27/84)
>My experience with the Sun 2 workstation is that it returns a value >which is printed via printf as "NAN" (not a number). I was under >the impression this had something to do with the IEEE standard >for floating point software. They claim they conform. My question >is whether or not they are consistent when using their Sky >hardware FP processor. >Bill Beblo In the sun architecture the math libraries sense the presence/absence of the Sky Fast Floating Point Processor Board, and automatically call it if present. There are compile options to force a non-transportable optimized compile which calls the Sky driver directly, rather than calling the math library and letting it decide. -- {ucbvax|decvax|ihnp4}!sun!sunny (Sunny Kirsten of Sun Microsystems)
geoff@callan.UUCP (08/31/84)
>My experience with the Sun 2 workstation is that it returns a value >which is printed via printf as "NAN" (not a number). I was under >the impression this had something to do with the IEEE standard >for floating point software. They claim they conform. My question >is whether or not they are consistent when using their Sky >hardware FP processor. > Bill Beblo > Bell Communications Research The Sky FP unit is IEEE-488, and thus will return NAN's and infinity when appropriate. The SUN printf routines recognize these as special cases and print them specially. Thus, I would expect all to work just find when using the Sky board. Isn't it interesting that Sunny Kirsten of Sun answered a totally different question that wasn't even raised in Beblo's posting, and the correct answer had to come from one of Sun's hottest competitors? -- Geoff Kuenning Callan Data Systems ...!ihnp4!wlbr!callan!geoff
geoff@callan.UUCP (Geoff Kuenning) (08/31/84)
Oops. My fingers got ahead of me. IEEE-488 is a bus; I don't know the number of the floating point standard off the top of my head. Anyway, the Sky FP is IEEE floating point, not IEEE-488. Sorry. -- Geoff Kuenning Callan Data Systems ...!ihnp4!wlbr!callan!geoff