log2

Computes the base 2 logarithm of vector elements.

Syntax

Buffer API:

void log2(queue &exec_queue, int64_t n, buffer<T, 1> &a, buffer<T, 1> &y, uint64_t mode = mode::not_defined, error_handler<T> errhandler = {})

USM API:

event log2(queue &exec_queue, int64_t n, T *a, T *y, vector_class<event> const &depends = {}, uint64_t mode = mode::not_defined, error_handler<T> errhandler = {})

log2 supports the following precisions and devices:

T

Devices supported

float

Host, CPU, and GPU

double

Host, CPU, and GPU

Description

The log2(a) function computes the base 2 logarithm of vector elements.

Argument

Result

Error Code

+1

+0

a < +0

QNAN

status::errdom

+0

-∞

status::sing

-0

-∞

status::sing

-∞

QNAN

status::errdom

+∞

+∞

QNAN

QNAN

SNAN

QNAN

Input Parameters

Buffer API:

exec_queue

The queue where the routine should be executed.

n

Specifies the number of elements to be calculated.

a

The buffer a containing input vector of size n.

mode

Overrides the global VM mode setting for this function call. See set_mode function for possible values and their description. This is an optional parameter. The default value is mode::not_defined.

errhandler

Sets local error handling mode for this function call. See the create_error_handler function for arguments and their descriptions. This is an optional parameter. The local error handler is disabled by default.

USM API:

exec_queue

The queue where the routine should be executed.

n

Specifies the number of elements to be calculated.

a

Pointer a to the input vector of size n.

depends

Vector of dependent events (to wait for input data to be ready).

mode

Overrides the global VM mode setting for this function call. See the set_mode function for possible values and their description. This is an optional parameter. The default value is mode::not_defined.

errhandler

Sets local error handling mode for this function call. See the create_error_handler function for arguments and their descriptions. This is an optional parameter. The local error handler is disabled by default.

Output Parameters

Buffer API:

y

The buffer y containing the output vector of size n.

USM API:

y

Pointer y to the output vector of size n.

return value (event)

Function end event.

Example

An example of how to use log2can be found in the Intel® oneMKL installation directory, under:

examples/sycl/vml/vlog2.cpp