RE: [GRASS5] Re: [GRASSweb-list]File radii.c

GRASS GIS GRASS GIS developer
1

I don't know for sure, BUT:
on page http://www.mentorsoftwareinc.com/cc/gistips/TIPS0899.HTM
down where it says "Meridional Radius of Curvature" is the exact formula
out of "radii.c". Quote: "essentially, the radius of curvature, at a specific latitude ...".

See also http://williams.best.vwh.net/ellipsoid/node1.html which has a nice
picture showning the parametric latitude and phi, the geodetic latitude.
On the next page,
http://williams.best.vwh.net/ellipsoid/node2.html, in equation 3, the
Meridional Radius of Curvature shows up.

So, it looks like you are calculating the Meridional Radius of Curvature
as a function of GEODETIC LATITUDE.

John

-----Original Message-----
From: grass5-admin@grass.itc.it [mailto:grass5-admin@grass.itc.it]On
Behalf Of Markus Neteler
Sent: Friday, September 30, 2005 10:02 AM
To: Helmut Kempelmann
Cc: grass5 developers list
Subject: [GRASS5] Re: [GRASSweb-list]File radii.c

A FWD from Weblist:

On Mon, Sep 12, 2005 at 01:53:37PM +0200, Helmut Kempelmann wrote:
> Dear Sirs,
>
> I think, all "lon"s in the file "radii.c" should read as "lat".
>
>
> regards,
> Kempelmann
>
> Elektroniksystem- und Logistik GmbH
> Dep VT - I, Dr. Helmut Kempelmann
> Einsteinstrasse 174
> D-81675 Muenchen
> Tel +49 (89) 9216 - 24 94
> Fax +49 (89) 9216 - 16 - 24 94
> e-mail Helmut.Kempelmann@esg.de
>

lib/gis/radii.c

can anyone confirm this?

Markus

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2

> > I think, all "lon"s in the file "radii.c" should read as "lat".

..

> lib/gis/radii.c
>
> can anyone confirm this?

Note that the three functions defined in radii.c do not appear to be
used anywhere in the source.

G_radius_of_conformal_tangent_sphere()
G_transverse_radius_of_curvature()
G_meridional_radius_of_curvature()

Hamish