New Focus Algorithm

[John Evans]

Hello Everyone,

Hope you're all well? I have been working on a change to improve focus on
my rig. Iterative and Polynomial don't work so well for me on the ASI EAF,
due, I think to backlash. The Linear algorithm works best but the second
pass usually overshoots the ideal focus position.

So I built a "Linear 1 Pass" algo, that is based on Linear for the 1st
pass, but instead of doing a second pass it moves straight to the minimum
of the first pass.

I've implemented a couple of curve types (Hyperbola and Parabola) using a
generic GSL curve fitting algorithm which could be extended in the future
if necessary. The fitting can be done either giving each point equal
weighting or weighting them based on the HFR standard deviation of the
stars.

See the enclosed document for more details.

I have written most of the code and it basically works on my rig and the
simulator. I have a couple of things still to work out though, and more
testing to do.

Since this is the first Kstars change I have done (using QT on Mac) I have
been following Ron Lancaster's work on getting Kstars running on Mac. In
terms of coding standards I've just followed what's been done in the areas
I've changed. If there are any resources that someone could point me to,
that would be great.

If anyone has any feedback on the change that would also be great (I'll
also post on the forum to see if there are any suggestions).

I estimate I'll be finished with coding and testing in a couple of weeks. I
would like feedback on deployment as I'm not familiar with the process at
all. So if anyone can point me to any resources that would be very helpful.

At the moment I'm thinking:
1. Release 1 - deploy Linear 1 Pass code but concentrate on minimising risk
to breaking existing code, esp the Linear algorithm. I have cloned some
Linear code for this.
2. Release 2. When Release 1 is working as expected, interface Linear 1
Pass code with Linear in a more integrated way, removing cloned code. If
any features of Linear 1 Pass would be useful for other focus algos, this
could be done here.

The reason I'm thinking of doing this in 2 steps is that I'm a novice with
C++ and this seems the best way to minimize the risks of breaking existing
code. However, I'm happy to take advice from more experienced people here.

If anyone would like to offer to help me, do a code review, etc., that
would be really appreciated. As I mentioned I'm a novice with C++ so
probably not doing things in the best way, but happy to be guided. Also,
any suggestions on:
1. Test cases to write for this change.
2. Best way to profile the code, test for memory leaks, etc.
3. Since this would run on a range of different machines, how to configure
for different setups, things to watch out for, etc.

Thanks for reading!

Regards,
John.
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