Developer Guide for Intel® oneAPI Math Kernel Library for Windows*
Setting the Default Mode of Vector Math with an Environment Variable
Intel® oneAPI Math Kernel Library (oneMKL) enables overriding the default setting of the Vector Mathematics (VM) global mode using the MKL_VML_MODE environment variable.
The default setting
The MKL_VML_MODE environment variable
A call vmlSetMode function
A call to any VM function other than a service function
For more details, see the Vector Mathematical Functions section in the Intel® oneMKL Developer Reference and the description of the vmlSetMode function in particular.
To set the MKL_VML_MODE environment variable, use the following command:
set MKL_VML_MODE=<mode-string>
In these commands, <mode-string> controls error handling behavior and computation accuracy, consists of one or several comma-separated values of the mode parameter listed in the table below, and meets these requirements:
Not more than one accuracy control value is permitted
Any combination of error control values except VML_ERRMODE_DEFAULT is permitted
No denormalized numbers control values are permitted
Values of the mode Parameter
Value of mode |
Description |
|---|---|
Accuracy Control |
|
VML_HA |
high accuracy versions of VM functions |
VML_LA |
low accuracy versions of VM functions |
VML_EP |
enhanced performance accuracy versions of VM functions |
Denormalized Numbers Handling Control |
|
VML_FTZDAZ_ON |
Faster processing of denormalized inputs is enabled. |
VML_FTZDAZ_OFF |
Faster processing of denormalized inputs is disabled. |
VML_FTZDAZ_CURRENT |
Keep the current CPU settings for denormalized inputs. |
Error Mode Control |
|
VML_ERRMODE_IGNORE |
On computation error, VM Error status is updated, but otherwise no action is set. Cannot be combined with other VML_ERRMODE settings. |
VML_ERRMODE_NOERR |
On computation error, VM Error status is not updated and no action is set. Cannot be combined with other VML_ERRMODE settings. |
VML_ERRMODE_ERRNO |
On error, the errno variable is set. |
VML_ERRMODE_STDERR |
On error, the error text information is written to stderr . |
VML_ERRMODE_EXCEPT |
On error, an exception is raised. |
VML_ERRMODE_CALLBACK |
On error, an additional error handler function is called. |
VML_ERRMODE_DEFAULT |
On error, an exception is raised and an additional error handler function is called. |
These commands provide an example of valid settings for the MKL_VML_MODE environment variable:
set MKL_VML_MODE=VML_LA,VML_ERRMODE_ERRNO,VML_ERRMODE_STDERR