Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

ID 766686
Date 3/22/2024
Public

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pilaenv

Returns the positive integer value of the logical blocking size.

Syntax

value = pilaenv (ictxt, prec )

Include Files

  • mkl_pblas.h

Description

pilaenv returns the positive integer value of the logical blocking size. This value is machine and precision specific. This version provides a logical blocking size which should give good though not optimal performance on many of the currently available distributed-memory concurrent computers. You are encouraged to modify this subroutine to set this tuning parameter for your particular machine.

Input Parameters

ictxt

INTEGER. On entry, ictxt specifies the BLACS context handle, indicating the global context of the operation. The context itself is global, but the value of ictxt is local.

prec

CHARACTER*1. On input, prec specifies the precision for which the logical block size should be returned as follows:

prec = 'S' or 's' single precision real,

prec = 'D' or 'd' double precision real,

prec = 'C' or 'c' single precision complex,

prec = 'Z' or 'z' double precision complex,

prec = 'I' or 'i' integer.

Application Notes

Before modifying this routine to tune the library performance on your system, be aware of the following:

  1. The value this function returns must be strictly larger than zero,

  2. If you are planning to link your program with different instances of the library (for example, on a heterogeneous machine), you must compile each instance of the library with exactly the same version of this routine for obvious interoperability reasons.