[GRASS5] r.mapcalc and NULL question
jhickey at hpcc.nectec.or.th
Tue Jan 16 03:44:39 EST 2001
Markus Neteler wrote:
> Generally I consider this as a bug because you can't always know if
> a map contains NULLs. If only a few pixels would be nulls you may
> use option 2 and don't realize that the result is not want you want.
> I feel this behaviour is somewhat dangerous. The isnull() is useful,
> but if you have to apply it on default in if-clauses, it's a bit
> Other comments?
I agree with the others, it is not a bug. Perhaps r.mapcalc should print
a warning if it tries to perform arithmetic on null values. At least
then, the user will be notified of the problem.
Jazzman (a.k.a. Justin Hickey) e-mail: jhickey at hpcc.nectec.or.th
High Performance Computing Center
National Electronics and Computer Technology Center (NECTEC)
People who think they know everything are very irritating to those
of us who do. ---Anonymous
Jazz and Trek Rule!!!
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