# [SciPy-dev] Latex and docstrings

Tom Grydeland tom.grydeland@gmail....
Wed Feb 17 04:22:17 CST 2010

On Wed, Feb 10, 2010 at 3:12 AM, David Cournapeau <david@silveregg.co.jp> wrote:
> Hi,
>
> I noticed that some of the docstrings I have written for DCT have been
> changed to latex format. While I have no issue with having latex in the
> documentation, I thought the consensus was to use them sparingly in
> docstrings ?

I am probably the one to "blame" here.  I know I have edited the DCT docstrings.

What is considered "sparingly" is obviously different from one person
to the next, and I have taken it to mean roughly "where pure text is
insufficient", and (along the discussion re numpy.fft and friends
<http://docs.scipy.org/numpy/docs/numpy.fft/>) okay for module-level
docstrings but avoid it for functions.  Since I have written a lot of
latex, I might have a lower threshold than others here.

> For example, the dct I formula used to be (fixed width font assumed):
>
> for 0 <= k < N,
>
>                                    N-1
> y[k] = x[0] + (-1)**k x[N-1] + 2 * sum x[n]*cos(pi*k*n/(N-1))
>                                    n=0
>
> But now, it is:
>
> y_k = x_0 + (-1)^k x_{N-1} + 2\\sum_{n=1}^{N-2} x_n
>         \\cos\\left({\\pi nk\\over N-1}\\right),
>         \\qquad 0 \\le k < N.
>
> I much prefer the former (the latter is unreadable in a terminal IMO). I
> have of course no issue in putting the latex formula in the scipy docs,

Similarly, the former is unreadable or incorrect in the web interface
where the latter is useful:
http://docs.scipy.org/scipy/docs/scipy.fftpack.realtransforms.dct/

If you change it back, please observe that the limits on the summation
are different for the two versions.

> David

Regards,

--
Tom Grydeland
<Tom.Grydeland@(gmail.com)>