[PROJ] Calculating meridian convergence

[Roger Oberholtzer]

On Wed, Jun 1, 2022 at 1:09 PM Thomas Knudsen <knudsen.thomas at gmail.com> wrote:

> The differing results from your code may be a matter of your PR instantiation leading to taking the code branch in https://github.com/OSGeo/PROJ/blob/ced8793aa170dd4792f331633e62726808a2e75d/src/4D_api.cpp#L2469
>
> Could you try to instantiate a plain, classic PROJ PJ using
>     proj_create("proj=tmerc lon_0=15 k_0=0.9996 x_0=500000 ellps=GRS80"),
> then calling proj_factors with that as input. It should send you through the code branch at https://github.com/OSGeo/PROJ/blob/ced8793aa170dd4792f331633e62726808a2e75d/src/4D_api.cpp#L2499 which may (or may not) give you the result you expect.
>
> If it doesn't, please file a ticket over at https://github.com/OSGeo/PROJ/issues

If I use the proj definition instead of the EPSG code, the calculation
works,. So I guess there is no bug to report for that.

The question is, should I be able to use the EPSG code here? Is this
an unintended thing that I cannot use it?



-- 
Roger Oberholtzer