[AstroPy] TAN WCS speedup

[Nadezhda Dencheva]

I just want to mention that some of the projections in WCS Paper II are 
implemented in astropy.modeling.projections.

Cheers,
Nadia
________________________________________
From: astropy-bounces at scipy.org [astropy-bounces at scipy.org] on behalf of Maik Riechert [maik.riechert at arcor.de]
Sent: Thursday, November 13, 2014 3:43 PM
To: Astronomical Python mailing list
Subject: [AstroPy] TAN WCS speedup

Hi,

I just finished implementing my own wcs_pix2world function specifically
for the TAN projection using just Python with numpy and numexpr. Without
numexpr I was slightly slower than astropy (15s vs 12.8s). But with
numexpr I got it down to 6.8s, so nearly twice as fast. This is for 8
million pixel coordinates as input run on my 2GHz Core 2 Duo Laptop
under Python 2.7 64 bit with Windows 7 and using Christoph Gohlke's
numpy and numexpr binaries.

I cannot post the code yet but the code is not that important anyway as
I didn't do really complicated things.

As numexpr seems to provide the main speedup, maybe some concepts of it
could be used to speedup astropy/wcslib. I guess it's not a sensible
option to actually implement all of wcslib in Python, given that there
are way more complicated projections etc. than TAN which would take
quite some time to reimplement/maintain.

This is basically it, just wanted to share that.

Cheers
Maik
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