[Proj] +a argument different than I expected

Frank Warmerdam warmerdam at pobox.com
Sun Nov 13 15:17:33 EST 2011

On 11-11-13 11:39 AM, Michael Speth wrote:
> Greetings,
> I am using SVN Revision: 2113. I have found that the +a argument doesn't match
> the value found in P->a. Here is an example:
> proj +proj=healpix -f '%.'$PERCISION'f' +lon_0=45 +a=3.0 +R_A +ellps=WGS84 -E <<EOF
> 0 0
> The value of P->a is 2.996646.
> Is this correct?


I don't really know the answer, but I'm guessing the +R_A is adjusting the
semi major and semi minor axis a bit.  I honestly don't even know what
you meant by the the mix of +a, +R_A and +ellps.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/warmerda
and watch the world go round - Rush    | Geospatial Software Developer

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