Re: Turbo C matherr() function

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2 total messages Started by RAMontante Fri, 03 Aug 1990 15:26

#1774

Author: RAMontante
Date: Fri, 03 Aug 1990 15:26

15 lines
1205 bytes

As Pete Holzmann says, matherr() only catches math errors in library
functions.  You must use the SIG_FPE/setjmp/longjmp facilities to
handle "lower-level" math errors.

I found that it was really hard to recover from a general math error ---
what do you want to do on divide-by-zero, for example?  Generate a
largest-possible-value? print a message? ... The simplest thing to do
is to simply clear everything out and longjmp back to some point in
your code that precedes the failed operation (and your error-handler
doesn't necessarily know where that is).

Plug:  I am told that my rpn calculator is queued for c.b.i.p.  It includes
source code, and I use both the matherr() and the SIG_FPE code to handle
math errors.  I don't claim it's the best example of such stuff, but it
*is* a working example...

Re: Turbo C matherr() function

#1832

Author: Bernie Roehl
Date: Wed, 08 Aug 1990 19:18

11 lines
841 bytes

Thanks for all the answers about matherr()... the bottom line seems to be that
I'll have to trap the errors using SIG_FPE instead of just writing my own
math handler.

Sigh.

-- 
	Bernie Roehl, University of Waterloo Electrical Engineering Dept
	Mail: broehl@watserv1.waterloo.edu OR broehl@watserv1.UWaterloo.ca
	BangPath: {allegra,decvax,utzoo,clyde}!watmath!watserv1!broehl
	Voice:  (519) 885-1211 x 2607 [work]

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