Forum Discussion
Error with Knitro tolerance parameters
Years ago, I used Knitro tolerance parameters XKTR_PARAM_OPTTOL and XKTR_PARAM_FEASTOL successfully. Now (FICO Xpress Mosel 64-bit v6.4.4, FICO Xpress v9.3.0), there seems to be an issue.
setparam() does not produce an error, or any output, but getparam() does:
Code:
writeln(">>>> XKTR_PARAM_OPTTOL = ", getparam("XKTR_PARAM_OPTTOL"))
writeln(">>>> XKTR_PARAM_FEASTOL = ", getparam("XKTR_PARAM_FEASTOL"))
Output:
?12001 Error: invalid parameter number 81027
?Error: (SLP) invalid parameter number 81027
>>>> XKTR_PARAM_OPTTOL = 0
?12001 Error: invalid parameter number 81022
?Error: (SLP) invalid parameter number 81022
>>>> XKTR_PARAM_FEASTOL = 0
What could be the reason? What is the right way to set these parameters and check their values?
By the way, I tried an alternative version of these parameters that I found in the doc: XPRS_KNITRO_PARAM_OPTTOL and XPRS_KNITRO_PARAM_FEASTOL. This gives a compilation error:
Control parameter `XPRS_KNITRO_PARAM_OPTTOL' unknown.
Thank you for your help!
Miroslav
7 Replies
Hi Miroslav. This is a bug: getparam is broken for Knitro parameters. I don't see any workaround for checking the values of these parameters but I am working on a fix. Setparam is unaffected, so you can continue to set the parameters as usual.
Hi Chris,
Makes sense. Thanks for confirming that setparam works for these parameters.
Regarding the alternative names of these parameters, XPRS_KNITRO_PARAM_OPTTOL and XPRS_KNITRO_PARAM_FEASTOL: Do you know why they give a compilation error? Are they supposed to be used in a different context?
Thank you,
Miroslav
I would consider that a bug too. I will fix both of these issues.
Both these issues will be fixed in the upcoming Xpress 9.5 release. They will also be fixed in the next available patches of earlier supported releases.
Thank you!
Slightly unrelated: What are the names of these parameters in Python API? I typically remove the "XPRS_" prefix but what are they here?
Thank you,
Miroslav
In Python they have the xktr prefix, e.g., problem.controls.xktr_param_opttol
Thanks a lot!
Miroslav
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