[Proj] Problems with Pittman geodesic??

[OvV_HN]

From: "Gerald I. Evenden" <geraldi.evenden at gmail.com>
Sent: Thursday, January 22, 2009 9:40 PM
Subject: Re: [Proj] Problems with Pittman geodesic??


> On Monday 19 January 2009 1:16:38 pm OvV_HN wrote:
>> Some time ago I referred to 2 articles by Saito.
....
>> Anyhow, he gives a couple of test points which everybody with geodesics
>> code definitively should try to replicate. You might be surprised!
> I did not find any surprises here because where problems do show up are 
> for
> the near apodal points which Vincenty (and others) usually flunk.

Nice. Indeed my implementation of NOAAs Vincenty went wrong with the 
antipodal examples 7, 8, 9. As did the earlier mentioned method of Xue-Lian 
Zhang.

>> Saito article 2 examples.
...
>> following results were obtained. The computation was made in double
>> precision arithmetic - through twenty significant digits.
> "double precision" --- "through twenty significant digits." ???  What kind 
> of
> hardware is being used?

The article is from 1978; only Fortran is mentioned.

> Using Gaussian Quadrature is not a big thing as long as one has the 
> integrals
> to evaluate---one does not need to use gsl to do that. ;-)

Then you probably don't need GNU GSL for the Mayr-Tobler projection!

Oscar van Vlijmen