[GRASS-dev] CELL/FCELL/DCELL [was: Re: r.mapcal rand() strangeness]

Hamish hamish_b at yahoo.com
Thu Feb 28 16:18:32 EST 2008

Maciej Sieczka wrote:
> Ok. But we need the minimum - what are the GRASS CELL, FCELL, DCELL
> and GRID3D.
> > BTW the info about CELL, FCELL and DCELL is in the man pages.
> Most complete info is in the raster intro AFAIK:
> ---
> Raster data can be stored in GRASS as a 2D integer grid, 2D floating
> point grid (single or double precision), or as a 3D floating point
> grid (single or double precision). The internal raster format is
> architecture independent and portable between 32bit and 64bit
> machines.  Internally, the integer format is called CELL, single
> precision floating point is called FCELL, double precision floating
> point is DCELL, and 3D raster is called GRID3D. The choice of the
> integer or floating point data depends on the application.
> ---
> Which doesn't explain what integer type is CELL. Now that Glynn 
> explained it in his other email:
>  > Oh, it's reasonable enough to document that (if it isn't already):
>  >
>  > 	CELL	32-bit signed integer
>  > 	FCELL	IEEE single-precision floating-point
>  > 	DCELL	IEEE double-precision floating-point

Include as *footnote for CELL? That way we don't disturb the flow of
the newbie doc with too much technical info, but it gets documented.
Worth the trouble?

IMO F+DCELL can live without the "IEEE" in the basic docs, if you start
with that do you have to explain nan vs NULL, inf vs ??, %.16g, ...?


ps- r.colors makes colr/ files like:

% -19.392855979271523381157749099657 95.629158236082361099761328659952

too much?

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