About r.surf.fractal

[Jacques Bouchard]

Venkatesh Raghavan wrote:

> Can anybody help me with getting the r.surf.fractal command running
> on Grass4.2. After I input all the necessary program parameters,
> to r.surf.fractal the program just hangs. I even tried to recompile
> r.surf.fractal but program still hangs.

I just tried to run r.surf.fractal from GRASS4.2.1 V19 (from Markus Neteler).
It does work. Here is what I get:

time r.surf.fractal out=fractal
Steps=1
Preliminary surface calculations.
Calculating surface 1 (of 1)
36.95user 3.45system 3:58.85elapsed 16%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (32474major+9493minor)pagefaults 9893swaps

in the following case:

My station:      Pentium 120 Mhz + 32 Mb RAM
My OS:           Linux Redhat 5.1
My GRASS region: spearfish/PERMANENT default (700 * 950 cells)

But there is indeed a problem: r.surf.fractal uses a *HUGE* amount of memory.
During my test, up to 45 Mb were used, so swapping occurred (30 Mb).

So if you haven't got enough swap space, you can't use r.surf.fractal.
You can close all your graphic applications (and even X11) to reduce
memory usage.

BTW, what is the use of r.surf.fractal ?

Jacques