Beefy Boxes and Bandwidth Generously Provided by pair Networks Frank
Perl Monk, Perl Meditation
 
PerlMonks  

Re^3: Answer: How do I create/detect/handle Infinity?

by ysth (Canon)
on Jul 26, 2009 at 10:12 UTC ( #783287=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Answer: How do I create/detect/handle Infinity?
in thread math

Yes. Other ways:

$isnan = ($x != $x); $isnan = ! defined($x <=> 0);


Comment on Re^3: Answer: How do I create/detect/handle Infinity?
Download Code
Re^4: Answer: How do I create/detect/handle Infinity?
by syphilis (Canon) on Jul 26, 2009 at 12:07 UTC
    $isnan = ! defined($x <=> 0);

    Ooow ... wasn't aware that perl did that.
    In the mpfr library, the mpfr_cmp(x,y) function will return -1 if x<y, +1 if x>y. Otherwise it returns 0 (and sets the erange flag iff one/both of the arguments is a nan).

    So, I'm left wondering whether, in Math::MPFR (which more-or-less wraps the mpfr library), the spaceship operator (which overloads the mpfr_cmp function) should:
    a) adhere to mpfr library behaviour and return 0 and set the erange flag when nans are involved;
    or
    b) adhere to perl behaviour and return undef when nans are involved.

    If b), then there's also the question of whether the erange flag should still be set.

    Interested to hear any thoughts on that.

    Cheers,
    Rob

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://783287]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others chilling in the Monastery: (9)
As of 2014-04-19 10:29 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    April first is:







    Results (480 votes), past polls