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OxfordIonTrapGroup / oitg

Python package of helper routines (result loading, fitting, etc) for the Oxford Ion-Trap Group (OITG).
https://oxfordiontrapgroup.github.io/oitg/
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Line fitting fails for two data points #36

Open mgely opened 3 years ago

mgely commented 3 years ago

The following code fails

from oitg.fitting import line
line.fit([0,1],[0,1])

with error

Traceback (most recent call last):
  File "C:\Users\LocalAdmin\Miniconda3\envs\artiq-env\lib\site-packages\oitg-0.1-py3.9.egg\oitg\fitting\FitBase.py", line 249, in fit
  File "C:\Users\LocalAdmin\Miniconda3\envs\artiq-env\lib\site-packages\scipy\optimize\minpack.py", line 795, in curve_fit
    res = least_squares(func, p0, jac=jac, bounds=bounds, method=method,
  File "C:\Users\LocalAdmin\Miniconda3\envs\artiq-env\lib\site-packages\scipy\optimize\_lsq\least_squares.py", line 805, in least_squares
    raise ValueError("`x0` is infeasible.")
ValueError: `x0` is infeasible.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "y:/testing/scratch_mfg/line_fit.py", line 2, in <module>
    line.fit([0,1],[0,1])
  File "C:\Users\LocalAdmin\Miniconda3\envs\artiq-env\lib\site-packages\oitg-0.1-py3.9.egg\oitg\fitting\FitBase.py", line 255, in fit
oitg.fitting.FitBase.FitError: `x0` is infeasible.

One obvious thing that would fail is the parameter_initialiser in line.py https://github.com/OxfordIonTrapGroup/oitg/blob/9b64b4e2c19d64926e5852bb2e16fca0b54ff230/oitg/fitting/line.py#L6-L9 which would give division by 0 errors for a size two array.