The CNR mode of

Intel® oneAPI Math Kernel Library

ensures bitwise reproducible results from run to run of

Intel® oneAPI Math Kernel Library

functions on a fixed number of threads for a specific Intel instruction set architecture (ISA) under the following conditions:

Intel® oneAPI Math Kernel Library

offers both functions and environment variables to support conditional numerical reproducibility. See the

Intel® oneAPI Math Kernel Library

Developer Guide

for more information on bitwise reproducible results of computations and for details about the environment variables.

The support functions enable you to configure the CNR mode and also provide information on the current and optimal CNR branch on your system. Usage Examples for CNR Support Functions illustrate usage of these functions.

Intel® oneAPI Math Kernel Library

provides named constants for use as input and output parameters of the functions instead of integer values. SeeNamed Constants for CNR Control for a list of the named constants.

Although you can configure the CNR mode using either the support functions or the environment variables, the functions offer more flexible configuration and control than the environment variables. Settings specified by the functions take precedence over the settings specified by the environment variables.

Use

Intel® oneAPI Math Kernel Library

in the CNR mode only in case a need for bitwise reproducible results is critical. Otherwise, run

Intel® oneAPI Math Kernel Library

as usual to avoid performance degradation.

While you can supply unaligned input and output data to

Intel® oneAPI Math Kernel Library

functions running in the CNR mode, use of aligned data is recommended. Refer toReproducibility Conditions for more details.