Intel® oneAPI Math Kernel Library Developer Reference - C
The concepts required to understand the use of the Intel® oneAPI Math Kernel Library preconditioner routines are discussed in theAppendix A Linear Solvers Basics.
The preconditioner routines take arrays of user data as input. To minimize storage requirements and improve overall run-time efficiency, the Intel® oneAPI Math Kernel Library preconditioner routines do not make copies of the user input arrays.
Some parameters of the preconditioners are common with the FGMRES Common Parameters. The routine dfgmres_init specifies their default and initial values. However, some parameters can be redefined with other values. These parameters are listed below.
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 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[1] - specifies the destination of error messages generated by the ILUT routine. The default value 6 means that all messages are displayed on the screen. Otherwise routine creates a log file called MKL_PREC_log.txt and writes error messages to it. 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 ILUT 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] - 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. The default value is 1.