Python module and wrapper for the LEVM complex nonlinear least squares (CNLS) program.
LEVM was written by J. Ross Macdonald. The LEVM Maunual can be downloaded here and provides a complete description of the LEVM program and how to set up a CNLS fit.
Example of use:
import levmpy as lv
expt = lv.Experiment("name-of-input-file", outsuffix="OUTFILE", path="path-name")To fit the data use the command:
expt.fit()To write the output to a file use:
expt.writetofile()The following class variables of the Experiment class may be useful:
| Variable | Description |
|---|---|
expt.freq |
frequency data |
expt.y |
immittance data (can use y1 and y2 for complex data) |
expt.r |
uncertainty on y (can use r1 and r2 for complex data) |
expt.parameters |
initial parameters |
expt.celcap |
empty cell capacitance |
expt.x |
fitted parameter estimates |
expt.rxsd |
relative standard deviation on x |
expt.nfrei |
number of free parameters |
expt.jac |
Jacobian matrix |
expt.outputvals |
model immittance data |
expt.res |
fit residual |
expt.resmod |
fit residual / model |
expt.md |
number of data points |
expt.info |
info flag from LMDER.f |
expt.fnorm |
L2 norm of residuals |
expt.nfev |
number of function evaluations |
expt.fqq |
fit quality factor |
expt.ndf |
number of degrees of freedom |
expt.dattyp |
data type (C, R or I) |
expt.freqtyp |
frequency type (F or None) |