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To: freebsd-questions@freebsd.org
Subject: Re: Behavior of sqrt on errors. 
Date: Fri, 30 Dec 1994 12:43:34 +0400
From: Feisal Mohammed <feisal@ldc.uwi.tt>
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Hi,

Mark Diekhans said,

>>> On FreeBSD,
>>> 
>>>    sqrt (-3.0);
>>> 
>>> generates a SIGFPE.  On all other systems I have encountered, it calls
>>> matherr with a DOMAIN error.  Can anyone more knowledgeable about the 
>>> ANSI standard comment if this correct ANSI behavior or a bug?

> In fact, this has to do with software (Tcl) that is ported to virtually 
> every Unix platform.  In all of those implementations, either matherr or
> returning a NAN (not-a-number) value is used to report the error.
> I have seen the port of Tcl on ftp.freebsd.org, it does a fpsetmask(0)

I use RLaB (a Matlab-like prog) under SunOS and also FreeBSD. The
differences of the implementation causes the floating pt. errors
to be handled less cleanly, e.g. 0/0 returns NAN on SunOS and
a floating exception on FreeBSD, same for sqrt(). Clearly the
better way is through the use of matherr as in SunOS.

-Feisal