[GRASS-user] r.sun out of memory bug with -m enabled?

[Jonathan Greenberg]

Folks:

I'm using r.sun with a set of precalculated r.horizon, and I'm getting
an out-of-memory error even with the -m flag enabled:

r.sun -s -m elevin=ned_ca_masked_epsg3310_comet_00008m at comet_common_01
aspect=270 slope=0.0 lin=3.0 alb=1
horizon=ned_ca_masked_epsg3310_00008m_horizon_ horizonstep=3
beam_rad=ned_ca_masked_epsg3310_comet_00008m_rsun_beam_015
diff_rad=ned_ca_masked_epsg3310_comet_00008m_rsun_diff_015 day=15
step=0.5 dist=1.0 numpartitions=1 --overwrite

I see that my numpartitions is too low, but from the r.sun manual:

memory_bytes = rows*cols*((IR*4+horizonsteps)/numpartitions  + OR*4)

Does this mean that the output files are stored in memory when I run
this?  So if I don't have 4 x the size of the raster in available RAM
(+ scratch) I can't run it?  If this is true, why doesn't GRASS do a
line-by-line (or chunk by chunk) write procedure?  Thanks!

--j