[GRASS-dev] r.mapcalc addition

Joel Pitt joel.pitt at gmail.com
Mon Apr 2 20:34:29 EDT 2007

Hi there, I was just checking the latest CVS and saw that my r.mapcalc
addition hadn't been added yet.

I was hoping someone with appropriate permissions could do so.

My dispersal simulation tool (which I hope to release properly in a
few months) requires the addition to function correctly.

Much thanks,

---------- Forwarded message ----------
From: Joel Pitt <joel.pitt at gmail.com>
Date: Oct 26, 2006 9:39 PM
Subject: Re: [GRASS-dev] r.mapcalc addition
To: Glynn Clements <glynn at gclements.plus.com>
Cc: Hamish <hamish_nospam at yahoo.com>, grass-dev at grass.itc.it

On 10/25/06, Glynn Clements <glynn at gclements.plus.com> wrote:
> > However, I'll follow Glynn's suggestion and read the seed in the
> > evaluate() function. This will be more robust if other functions are
> > implemented that call the RNG.
> >
> > On this topic, would there be any call for implementing more
> > complicated probability distribution functions? Or is the philosophy
> > of mapcalc to have the simplest elements necessary?
> A Gaussian distribution might be useful, as you can't readily
> implement that using existing r.mapcalc functions (the usual
> implementation uses iteration, which r.mapcalc doesn't support).
> For enhancements which might be useful to other users, I'd suggest
> posting an announcement (or the code itself) to the list. If enough
> people express an interest in having the functionality built in, we
> can add it.
> Adding new functions is quite straightforward; OTOH, we don't want to
> bloat r.mapcalc with code which is unlikely to be used by anyone but
> its author.
> For more complex tasks, there's always R/GRASS. r.mapcalc will always
> be bound by its structural limitations (row-by-row processing,
> inability to define new functions, etc).

I've attached a diff of evaluate.c and the related html files that I'm aware of.

Turns out it was alot simpler adding the functionality as a environment variable


"Wish not to seem, but to be, the best."
                -- Aeschylus


"Unless you try to do something beyond what you have mastered, you
will never grow." -C.R. Lawton
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