Warning: Derivative finite differencing was artificially reduced to be within bound constraints

I am getting this error when running the file select.m in this post processing

 Warning: Derivative finite-differencing step was artificially reduced to be within bound constraints. This 
 may adversely affect convergence. Increasing distance between bound constraints, in dimension 80, to be at 
 least 2.2e-20 may improve results. 

 > In fwdFinDiffInsideBnds
  In finitedifferences
  In computeFinDiffGradAndJac
  In barrier
  In fmincon (line 800)
  In select (line 64)

[Torsten]

You seem to define the upper bound u and the lower bound l for a solution variable such that u is equal to l. That's not good. Instead, if you want the variable to be a constant, you should define A_eq and b_eq appropriately.

Best wishes

Torsten.

[John D'Errico]

Never try to fix a variable to be constant by setting bounds that try to make it so. Instead, replace the variable by a constant.

Answer 1

[Suhan]

Hi Tejas,

This error may occur if you have tolerances that are implausible for the order of magnitude of the data and because the bounds placed on some of the parameters force it to be implausible to find a solution.

To fix this, use realistic bounds and tolerances as well centering and scaling the fit.