Developer Reference

Contents

ILU0 and ILUT Preconditioners Interface Description

The concepts required to understand the use of the
Intel® MKL
preconditioner routines are discussed in theAppendix 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® MKL
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
specifies their default and initial values. However, some parameters can be redefined with other values. These parameters are listed below.
For the ILU0 preconditioner:
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.
For the ILUT preconditioner:
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.

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804