README

Saltype stands for Symbolic Algebra Light Type, and is also a common additive in food preparation, which makes the name fit in the palette of software developed by me. Salt (as NaCl) is also a substance that can be found in high quantities in nature. This can be seen in parallel to saltype being developed to obtain derivatives of large scale systems, well at least a couple of thousand variables.

For the detailed documentation, see here: https://saltype.readthedocs.io/en/latest/index.html

How do I get set up?

pip install saltype

There are no dependencies outside the standard python library to use saltype.

BTW: I first called this salt, then salty, and each time somebody else created another package on pypi with the same name. Now I'll try to upload this before it happens again.

Teaser

The core functionality is demonstrated by this very simple example:

from saltype import Leaf
from saltype.tools import Derivative

x = Leaf(3.0)
y = 3 * x**2 + 2*x + 1

dy_dx = Derivative([y], [x])[0, 0]
print(dy_dx.value)  # = 6 * x + 2 = 20

In applications, we use this package to generate and evaluate Jacobian matrices of O(10000). Then it takes typically O(10) seconds to generate the Jacobian and O(1) second to evaluate it in each iteration. Of course, our Jacobians are also sparse, with less than 50 non-zero elements per row.

For developing ...

sphinx is required to build the documentation, and pytest is handy to run the tests, though they also run on the stdlib unittest module.

To build the documentation from the repo, enter the gendoc directory and run

make html

As being generic functionality of sphinx, this should work on Linux, Wintendo and Mac.

There are a number of unit tests in the unittest directory. Run

Contribution guidelines

Well, let's first get a star on github, before we talk about somebody else being interested in taking this further. Honestly, for many purposes, casadi is a better choice here, but if you just need something lightweight, maybe on embedded systems, then this might actually be the niece for salttype.

Contributions in the shape of coding and suggestions are welcome. The issue tracker is open for that.