Here the answer/solution from Laura. I have backported her fix to 6.4.svn. Markus
On Tue, Aug 26, 2008 at 5:47 PM, Laura Toma <[EMAIL PROTECTED]> wrote: > Hi Markus, > > They are right, the ratio of flow to contour can be smaller than 1, so > there is no need for tci to be positive. > > I commented out the warning in the grass_trunk. I don't have a working > version of grass6_devel, so if it needs to be changed there as well, maybe > somebody can copy it over. > > -Laura > > > On Aug 26, 2008, at 5:07 AM, Markus Neteler wrote: > >> Hi Laura, >> >> do you have any suggestion here? >> >> Thanks >> Markus >> >> >> ---------- Forwarded message ---------- >> From: roderikk <[EMAIL PROTECTED]> >> Date: Mon, Aug 25, 2008 at 10:51 AM >> Subject: Re: [GRASS-dev] r.terraflow performance tweak >> To: [email protected] >> >> >> >> Hi all, >> >> I am trying to use r.terraflow now as well to analyse a very large >> dataset. >> However, I run into the same issue as the OP. I get millions of warning >> messages that are not really relevant, because a negative tci is in my >> eyes >> just valid, however, adding an hour to my initial test run on a smaller >> sample. >> >> I think the check on line 143 of sweep.cc should see if the flow or the >> slope are negative (giving rise to the log of a negative number resulting >> in >> an error). I am not sure yet what a negative tci means, but a small flow >> with a large slope will result in a ratio smaller than 1 giving a negative >> value for the logarithm taken. >> >> Has any work been done on this? >> >> Sincerely, >> >> Roderik >> >> >> >> >> Ludwig M Brinckmann wrote: >>> >>> Looking through the code of r.terraflow I discovered that there is one >>> compile time only option that significantly reduces/improves the >>> performance >>> of r.terraflow. At the moment builds produce the less performant version >>> by default, which for such a long running program is not good. Only those >>> who read and modify the source code can get the faster version. >>> >>> options.h, l. 47, #defines OUTPUT_TCI by default, causing additional >>> files >>> generated and in my case a significant (I think millions) number of error >>> messages from this TCI option from sweep.cc line 143 (tci negative). >>> >>> Not being a GIS person I have no idea what the error means, the output >>> from >>> r.terraflow seemed to correlate with reality despite the message, and >>> even >>> the author of this bit seemed not sure what the error signified: see line >>> 141: is this true?. Printing the error a zillion times added a night to >>> my program run. _______________________________________________ grass-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-dev
