False warnings from dfgmres_check()

[mecej4]

The DFGMRES example provided with MKL 2021.2 runs fine as it did with earlier versions of MKL, but it emits a number of false warnings.

This happens with both the Fortran (fgmres_full_funct.f90) and C (fgmres_full_funct.c) examples. The warnings are output when DFGMRES_CHECK is called.

------------------------------------------------------------------------------
Intel MKL RCI FGMRES WARNING:
Parameters IPAR(1), IPAR(15) and IPAR(16) have incompatible values.
Some of these parameters were probably altered after DFGMRES init routine.
Some of these parameters were probably altered after DFGMRES init routine.

The dashed line and the next four lines are repeated five more times, with 17, 18, 19, 20 and 21 in place of "16" in the second line .

The results are fine, the warnings are spurious. With an older version of Parallel Studio (PS2016), and the MKL that it came with (11.3.4), these spurious warnings are not seen.

[Kirill_V_Intel]

Hello @mecej4,

We decided to emit these warnings (and actually return a new non-zero error code) intentionally.

In the past, dfgmres_init did not initialize certain parameter values and dfgmres_check had an unexpected side effect of silently initialiazing = changing parameters and hence was not just a "check" and was not optional opposite to what the documentation stated.

Per request of a customer, we fixed this behavior. Now, dfgmres_init initializes ipar. Then it is up to the user to change parameters (optionally) and call dfgmres_check which checks the parameters and if finds a discrepancy, fixes it (and emits a warning).

Are these warnings a problem for you? You should be able to turn them off by changing the ipar which controls verbosity of the output.

Best,
Kirill

[mecej4]

No, it is not a problem. I was just surprised by seeing an Intel-provided example giving lots of warnings.

Thanks.

[Kirill_V_Intel]

Thanks for the feedback! We'll consider turning these warnings off in the examples by decreasing output verbosity througn ipar.

Best,
Kirill

[Gennady_F_Intel]

in case, if the warnings are the problem, changing the default values of ipar[5] and ipar[6] will help to eliminate all warnings.

see more from https://software.intel.com/content/www/us/en/develop/documentation/onemkl-developer-reference-fortran/top/sparse-solver-routines/iterative-sparse-solvers-based-on-reverse-communication-interface-rci-iss/fgmres-interface-description.html#fgmres-interface-description_RCI_ID_COMMONPARAMETERS

[Gennady_F_Intel]

The issue is closing and we will no longer respond to this thread. If you require additional assistance from Intel, please start a new thread. Any further interaction in this thread will be considered community only.