<br><br><div class="gmail_quote">On Fri, Nov 25, 2011 at 4:31 AM, Andy Wickert <span dir="ltr"><<a href="mailto:andrewwickert@gmail.com">andrewwickert@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hi Grass-dev,<br>
<br>
I ran into an unexpected issue (to me, at least) with r.mapcalc:<br>
I was multiplying and dividing by some pretty big scalars, and one of<br>
those was greater than a 32-bit signed value (so >2**31). What mapcalc<br>
did was to reduce that value to 2**31 and carry on with operations.<br>
There was no warning, and I didn't find any information about this on<br>
the r.mapcalc help page, so I just wanted to alert (or possibly<br>
remind) the list that this exists and note that (as a non-developer)<br>
it took me a while to figure out that this was a problem. If there is<br>
an easy way to throw an error instead of silently hitting a ceiling,<br>
or this would be important enough to put on the manual webpage, I<br>
think it would be helpful, and certainly would have saved me a ton of<br>
time.<br></blockquote><div><br>I ran into the same issue when I was using integers - I solved it by converting the raster to double. But I agree with Andy: I think GRASS should throw an error when the rollover occurs, or use a dedicated value in this cell, so that one can check afterwards. Thinking about it: an error is asked for, as something went wrong.<br>
<br>Cheers,<br><br>Rainer<br> <br></div><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
Thanks, and happy Thanksgiving to those in the USA!<br>
<br>
Andy<br>
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</blockquote></div><br><br clear="all"><br>-- <br>Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology, UCT), Dipl. Phys. (Germany)<br><br>Centre of Excellence for Invasion Biology<br>Stellenbosch University<br>
South Africa<br><br>Tel : +33 - (0)9 53 10 27 44<br>Cell: +33 - (0)6 85 62 59 98<br>Fax (F): +33 - (0)9 58 10 27 44<br><br>Fax (D): +49 - (0)3 21 21 25 22 44<br><br>email: <a href="mailto:Rainer@krugs.de" target="_blank">Rainer@krugs.de</a><br>
<br>Skype: RMkrug<br><br>