About r.surf.fractal

[Venkatesh Raghavan]

Hi,
Jacques Bouchard wrote:

> BTW, what is the use of r.surf.fractal ?
>
I am developing a program to calculate fractal dimension of topographic
surfaces using DEM. I hope to check if is working okay using the
synthetic fractal surfaces generated by r.surf.fractal.

How long did it take to generate the output file "fractal" on your
machine?

> 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.