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From: gwyn@brl-tgr.ARPA (Doug Gwyn )
Newsgroups: net.bugs.4bsd
Subject: Re: libm---log(negative)
Message-ID: <8190@brl-tgr.ARPA>
Date: Sun, 10-Feb-85 16:28:49 EST
Article-I.D.: brl-tgr.8190
Posted: Sun Feb 10 16:28:49 1985
Date-Received: Tue, 12-Feb-85 05:54:07 EST
References: <130@entropy.UUCP>
Distribution: net
Organization: Ballistic Research Lab
Lines: 10

> Anyway, does anyone,
> besides me, think it would be a good idea to explicitly warn the user
> when s/he attempted to call log with a negative argument?  If so,
> have you come up with a smooth way of doing it?

Yes, on UNIX System V there is a matherr(3M) library function that
is invoked when a math library routine detects an error.  By default
it prints an appropriate warning message on stderr.  The programmer
can provide his own matherr() and do whatever he thinks is appropriate
upon occurrence of a math library error.