[GRASS5] floating AI ASCII GRID import

Frank Warmerdam fwarmerdam at gmail.com
Sat Nov 27 11:53:57 EST 2004

Maciek Sieczka wrote:

> The value range should be:
> min=176.945400
> max=284.015600
> And it is the case when 'r.in.arc type=DCELL' is used for importing.
> However, if 'r.in.gdal' or 'r.in.arc type=FCELL' is used then:
> min=176.945404
> max=284.015594
> I suppose there should be no difference. What is the reason?


Well, the obvious conclusion is that a FCELL, which I presume reads as a 
4byte float gives
slightly less precision than DCELL which is an 8byte float.  The change 
in the seventh digit would
seem to be what we would expect from floating point precision limitations.

Best regards,


I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
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and watch the world go round - Rush    | Geospatial Programmer for Rent

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