Developer Reference for Intel® oneAPI Math Kernel Library for C
ILU0 and ILUT Preconditioners Interface Description
The concepts required to understand the use of the Intel® oneAPI Math Kernel Library (oneMKL) preconditioner routines are discussed in the Appendix A: Linear Solvers Basics.
User Data Arrays
The preconditioner routines take arrays of user data as input. To minimize storage requirements and improve overall run-time efficiency, the Intel® oneMKL preconditioner routines do not make copies of the user input arrays.
Common Parameters
Some parameters of the preconditioners are common with the FGMRES Common Parameters. The routine dfgmres_init (Initializes the solver) specifies their default and initial values. However, some parameters can be redefined with other values for ILU/ILUT preconditioners beyond what is described for FGMRES. These parameters are listed below.
Parameter |
Description |
|---|---|
ipar[1] |
Specifies the destination of error messages generated by the ILU0 routine. The default value 6 means that all error messages are displayed on the screen. Otherwise routine creates a log file called MKL_PREC_log.txt and writes error messages to it.
NOTE:
Note if the parameter ipar[5] is set to 0, then error messages are not generated at all.
|
ipar[5] |
Specifies whether error messages are generated. If its value is not equal to 0, the ILU0 routine returns error messages as specified by the parameter ipar[1]. Otherwise, the routine does not generate error messages at all, but returns a negative value for the parameter ierr . The default value is 1. |
ipar[6] |
Modifies warning message approach. The default value is 1. If its value is greater than 0, the ILUT routine generates warning messages as specified by the parameter ipar[1] and continues calculations. If its value is equal to 0, the routine returns a positive value of the parameter ierr . If its value is less than 0, the routine generates a warning message as specified by the parameter ipar[1] and returns a positive value of the parameter ierr. |