[PROJ] Horner - polynomial solving in 3D

[Thomas Knudsen]

Probably not possible: proj=horner is meant for evaluating 2D polynomials,
where,
if I understand your situation correctly, you need to evaluate three 1D
polynomials.

Also, proj=horner computes polynomial corrections, which are added to your
input coordinates,
for the final output. So all in all a quite different situation from
obtaining the bare polynomial values.
So I believe this most likely is not the tool you are looking for.

Den tors. 30. apr. 2026 kl. 01.54 skrev Norman Barker via PROJ <
proj at lists.osgeo.org>:

> Hi,
>
> Looking at
> https://proj.org/en/stable/operations/transformations/horner.html it
> mentions the domain being 2D and 3D. I also looked at the code and read
> more about Horner and it seems that I can apply Horner on two dimensions
> and then the third.
>
> My problem is that I have a moving coordinate frame (in ECEF) that is a
> function of time, it is representing a sensor in space. Each frame unit
> vector UX, UY, and UZ is specified as the coefficients of a polynomial in
> X, Y, and Z (ECEF) that is dependent on time (t).
>
> Using a proj string I am hoping that I can pass in a coordinate `t` to
> generate the XYZ coordinates which I can then pass down the pipeline.
>
> Is this possible, if so how do I use Horner with three dimensional data?
>
> Many thanks,
>
> Norman
>
>
> _______________________________________________
> PROJ mailing list
> PROJ at lists.osgeo.org
> https://lists.osgeo.org/mailman/listinfo/proj
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/proj/attachments/20260430/136ef782/attachment.htm>