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[bug-gawk] Gawk and NaN values
From: |
Hermann Peifer |
Subject: |
[bug-gawk] Gawk and NaN values |
Date: |
Wed, 31 Aug 2011 19:38:37 +0200 |
User-agent: |
Mozilla/5.0 (Windows NT 5.1; rv:6.0) Gecko/20110812 Thunderbird/6.0 |
Hi,
The manual states on p. 346 about nan and inf:
--- snip ---
gawk interprets the four strings ‘+inf’, ‘-inf’, ‘+nan’, and ‘-nan’
specially, producing the corresponding special numeric values. The
leading sign acts a signal to gawk (and the user) that the value is
really numeric... For example:
$ echo +nan | gawk '{ print $1 + 0 }'
-| nan
--- snip ---
The result above is 'nan', i.e. a string without a leading sign which
means that subsequent awk processing will not detect that this is meant
to be a special value. Simplified example:
$ echo "1 -nan" | awk '{ print $1, $1 / $2 }'
1 nan
$ echo "1 -nan" | awk '{ print $1, $1 / $2 }' | awk '{print $1 / $2}'
awk: cmd. line:1: (FILENAME=- FNR=1) fatal: division by zero attempted
This might well be a feature rather than anything else. I just came
across it today and thought it could be worth reporting.
Hermann
- [bug-gawk] Gawk and NaN values,
Hermann Peifer <=