Pardiso bunch-kaufman pivoting option 3 different in MKL 2025.0.1

[StefanV1]

When using PARDISO with iparm[20]=3, behavior has changed between MKL 2024.2 and 2025.0. It seems that it does not perform the solve step anymore. With 2024.2, the log said ``` Times: ====== Time spent in direct solver at solve step (solve) : 0.000027 s Time spent in additional calculations : 0.000005 s Total time spent : 0.000032 s ``` Now the line "Time spent in direct solver at solve step (solve)" disappeared and the returned solution is different. (https://github.com/coin-or/Ipopt/issues/799) Is this a know issue? Is this a feature or bug?

[Ruqiu_C_Intel]

Hi Stefan,

Thank you for posting the issue.

We can reproduce it on our side. If you set iparm[20]=0 or 1, the disappeared message will reappear.

May I ask what is the typical value of max_iterref_steps in your application? Also could you tell us how important is this issue to your project? Does this issue hinder your work? 

Best regards,

Ruqiu

[StefanV1]

iparm[7] (max_iterref_steps) is currently set to 1 by default. Having iparm[20]=3 and iparm[7]=2 (the default) or iparm[7]=10 does not work. But setting iparm[20]=3 and iparm[7]=0 seems to work.

Since we have workarounds (iparm[20]=0 or 1, iparm[7]=0, or using an older MKL), this issue is not a serious blocker.

[Ruqiu_C_Intel · Accepted solution]

Thanks to Stefan for letting us know that this is not a serious issue.

We will fix it in a future release.