Expfit is a lightweight Python package to fit exponentials to noisy time series, typically with the aim of extracting time constants.

It aims to meet the following goals:

• Fit scaled and vertically transposed exponentials y = a + b * exp(c * x) without requiring initial parameter estimates.
• Fit double, triple, and quadruple exponentials y = a + b_i * exp(c_i * x) where each exponential term is decaying (c_i < 0) and all b_i have the same sign.
• Fit multiple decaying exponentials in data with multiple b_i signs.
• Be lightweight: use good initial strategies and properties of exponentials to simplify the optimisation problem.

Although a relatively simple task, expfit has unit tests, and reported failures will be added to its test suite to create a reliable tool for this sometimes fiddly operation.

Does single exponentials well

Building on initial guesses for single, also started adding double which it does OK

To install from the repo, use e.g.

python setup.py install -e .

Tests can then be run with

python -m unittest

And coverage can be tested with

python -m coverage run
python -m coverage report