Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!csus.edu!borland.com!alexande
From: alexande@borland.com (Mark Alexander)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Borland C and _8087/matherr bugs? HELP
Keywords: Borland C FPU 8087
Message-ID: <1991May7.171822.10242@borland.com>
Date: 7 May 91 17:18:22 GMT
References: <2397@wet.UUCP>
Organization: Borland International
Lines: 21

In article <2397@wet.UUCP> smiller@wet.UUCP (Gregory Shane Miller) writes:
>On a related issue, what gives with the matherr function?  On my system,
>the FPU is so slow that if my AT is in turbo mode the CLK FREQ to the
>'287 causes wierd overflow errors.   To test that, I wrote a 2 line program:
>
>double x,y;
>main()
>{
>       y = (double).32432432;
>       x = y/M_PI;
>}
>
>And when you run the program it terminates: Floating point error: overflow
>*NOW* if I write my own matherr() function to catch any FP exceptions and
>use the same code above - my matherr() is never called.   OK - running the
>poor chip too fast isn't too smart but why no consistency?

The error message was printed by the FPU exception (NMI) handler in
the library, not by matherr().  Matherr() handles errors for the math
library (negative numbers passed to log(), etc.).  You can trap
FPU exceptions by using signal(SIGFPE,...).