in reply to Re: Perl returns NaN after addition
in thread Perl returns NaN after addition

What is the regex for testing if a variable is NaN? and warnings did not spit out anything. thanks!

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Re^3: Perl returns NaN after addition
by LanX (Saint) on Oct 17, 2013 at 01:09 UTC
    from FAQ

    Scalar::Util (distributed with 5.8) provides access to perl's internal function looks_like_number for determining whether a variable looks like a number.


    despite older discussions recommending that way I do have problems on my system:

    DB<243> $nan=sin(9**9**9) => "nan" DB<244> looks_like_number($nan) => 8704 DB<245> $nan eq "nan" => 1 DB<246> Scalar::Util::looks_like_number($nan) => 36

    I know that NaN is plattform/C-compiler depended, so better test which way works.


    according to perlop#Equality Operators

    DB<106> $nan=sin(9**9**9) => "nan" DB<107> print "NaN support here" if $nan != $nan => 1 NaN support here DB<108>

    Cheers Rolf

    ( addicted to the Perl Programming Language)