[fpc-pascal] math with infinity and NaN

[James Richters]

SetExceptionMask(GetExceptionMask + [exInvalidOp]);   Works!    Thank  you for the help!

I'm curious why things like SQRT(-1) just produce NAN without needing to change the exception mask and (+inf) - (+inf) does not behave the same way.  They both are invalid,  why treat one method of generating an invalid number one way and another method of getting just as invalid of a number another way?  If there is flexibility in the standard, then why not choose to always be consistent?    I have a lot of examples of things that do produce NAN without needing to change the exception mask... like ln(-1) or 0/0  why do some cause the exception and others do not? 

If someone wanted to volunteer time to adjust the math unit to always behave the same way, would it be something that would be accepted or is there some fundamental reason why it is like this?

James


-----Original Message-----
From: fpc-pascal [mailto:fpc-pascal-bounces at lists.freepascal.org] On Behalf Of Sven Barth via fpc-pascal
Sent: Wednesday, June 20, 2018 5:23 PM
To: fpc-pascal at lists.freepascal.org
Cc: Sven Barth <pascaldragon at googlemail.com>
Subject: Re: [fpc-pascal] math with infinity and NaN

Am 20.06.2018 um 23:15 schrieb James Richters:
> Is there a way to prevent getting the runtime error?

=== code begin ===

SetExceptionMask(GetExceptionMask + [exInvalidOp]);

=== code end ===

Regards,
Sven
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