GSoC Week 6
I successfully passed my mid term evaluation this week and now the second half
of my project has begun! It has been a challenging journey so far that has made
me explore new algorithms (some very ingenious) and read a lot of code (much
more difficult than I had imagined). This week, Mario whose code I am
working on, helped in a big way by showing how and where to improve the
algorithms. It is clear now that all the functions need to guarantee the order
of the series they output. We were planning to keep it optional but since
ring_series
functions each other, an error in the order will propagate and
eventually make it unpredictable.
So Far
PR 9575 is ready for merge except
for a bug in sympify
that converts PythonRational
into float.
I had a discussion with Mario on PR 9495. He has suggested a lot of improvements while dealing with fractional exponents, especially the fact that Newton method may not be ideal in these cases. It is very interesting to try and compare different algorithms and come up with ways to optimise them for out needs. The scope for improvement is immense and we'll need to decide the order in which we'll push the optimisations.
I started writing the RingSeries
class for series evaluation in PR
9614. I was supposed to update my
blog yesterday, but I dozed off while working on it. According to my current
approach, I am writing classes for all the functions so that they can be
represented symbolically. Another issue that needs to be tackled is expansion of
nested functions, things like sin(cos(sin(x))
. This will need some work as
there are many approaches to tackle it. Currently, I evaluate the inner
functions( it they exist) recursively with prec + 1
. This will work in simple
cases, but not if there are cancellations, eg, sin(cos(x))  sin(cos(x**2))
.
Next Week

Get PR 9575 merged.

Improve PR 9495 and get it merged.

Finalise the series class hierarchy and the
series
evaluation function.
The next phase of my project is in Symengine and there have been a lot of
improvements and changes there. I will need to play with the new stuff and
perhaps also think of ways to port ring_series
there.
Cheers!
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