It looks like you had a non-numeric variable in the data file!

> so how would I test for that?

stop reading the file as soon as you get NaN. Print the line number '$.' and dump line and column with Data::Dumper

BTW: did you use warnings?

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

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.

update

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
[download]

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

update

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>
[download]

Cheers Rolf

( addicted to the Perl Programming Language)

or, if the OP happens to use Math::BigFloat:


$ perl -MMath::BigFloat -wE 'say Math::BigFloat->new(5) + "foo"'
NaN
[download]

or, if the OP happens to use Math::BigFloat

It's interesting that Math::BigFloat decides it has to numify a non-numeric string to NaN ... when everything else numifies such a string to zero.

Actually, I'm tempted to s/interesting/stupid/, but maybe there's a precedent somewhere that gives some credence to the Math::BigFloat behaviour.

Cheers,
Rob