This a thousand times over. Academic code will take every shortcut and simplification possible. Hardcoded values, globals, no modularity, no error checking, shared-everything architecture assumptions, single-letter variables with mixed naming convention, anything to get the job done.

Once the paper is written, the data analyzed, the project is done. There is no such thing as "maintainability" because the code isn't used past publication.

In mathematical code, single letter variables are often the clearest. "Descriptive" names only obfuscate the meaning further, because the meaning is in the math.

I've translated several mathematical papers into code, and I must strongly disagree. The very first thing I do is translate glyphs into names relevant to the domain I'm applying the math to. It makes the rest of the process immensely easier.

I guess we'll have to agree to disagree then. I too have coded up a lot algorithms from academic papers. In my mind,

yk = C * xk + D * uk

is a lot clearer than

position_at_time_k = output_matrix * state_at_time_k + feedthrough_matrix * input_at_time_k.

The first is an idiom. The second is not.

That may make sense internal to a library, where you’ve established idioms.

But as a counterpoint, I only know what you meant by the first expression because I read the second expression.

I actually agree with you in large part, that short variable names can have more meaning within an established set of idioms because they allow you to parse whole statements at once. But there’s a trade-off involved, because mathematics can take symbology further than that’s useful.

For example:

    E[i=0;5](i**2)

    sum([i**2 for i in range(0,5)])

So it often comes down to a matter of taste.

Why not something like this?

    position = C * state + D * input

Reasoning: k is the only subscript, so it can be dropped. Meaning of C and D are implicitly defined through their function wrt to state and input, so its OK not to name them. It also keeps the structure visible similar to that of the math.