Ill Conditioning Certificate

This module contains a tool for determining whether a model is ill-conditioned.

idaes.core.util.diagnostics_tools.ill_conditioning.compute_ill_conditioning_certificate(model, target_feasibility_tol=1e-06, ratio_cutoff=0.0001, direction='row')

Finds constraints (rows) or variables (columns) in the model Jacobian that may be contributing to ill conditioning.

This method is based on work published in:

Klotz, E., Identification, Assessment, and Correction of Ill-Conditioning and Numerical Instability in Linear and Integer Programs, Informs 2014, pgs. 54-108 https://pubsonline.informs.org/doi/epdf/10.1287/educ.2014.0130

Parameters:

• model – model to be analysed

• target_feasibility_tol (float) – target tolerance for solving ill conditioning problem

• ratio_cutoff (float) – cut-off for reporting ill conditioning

• direction (str) – ‘row’ (default, constraints) or ‘column’ (variables)

Returns:

list of strings reporting ill-conditioned variables/constraints and their associated y values