# atan2pi¶

Computes the four-quadrant inverse tangent of the ratios of the corresponding elements of two vectors divided by `π`.

Syntax

Buffer API:

void `atan2pi`(queue &exec_queue, int64_t n, buffer<T, 1> &a, buffer<T, 1> &b, buffer<T, 1> &y, uint64_t mode = mode::not_defined)

USM API:

event `atan2pi`(queue &exec_queue, int64_t n, T *a, T *b, T *y, vector_class<event> const &depends = {}, uint64_t mode = mode::not_defined)

`atan2pi` supports the following precisions and devices:

T

Devices supported

`float`

Host, CPU, and GPU

`double`

Host, CPU, and GPU

Description

The atan2pi(a,b) function computes the four-quadrant inverse tangent of the ratios of the corresponding elements of two vectors divided by `π`.

For the elements of the output vector `y`, the function computers the four-quadrant arctangent of `a`i/`b`i, with the result divided by `π`.

Argument 1

Argument 2

Result

Error Code

-∞

-∞

-3/4

-∞

`b` < +0

-1/2

-∞

-0

+1/2

-∞

+0

-1/2

-∞

`x` > +0

-1/2

-∞

+∞

-1/4

`a` < +0

-∞

-1

`a` < +0

-0

-1/2

`a` < +0

+0

-1/2

`a` < +0

+∞

-0

-0

-∞

-1

-0

`b` < +0

-1

-0

-0

-1

-0

+0

-0

-0

`b` > +0

-0

-0

+∞

-0

+0

-∞

+1

+0

`b` < +0

+1

+0

-0

+1

+0

+0

+0

+0

`b` > +0

+0

+0

+∞

+0

`a` > +0

-∞

+1

`a` > +0

-0

+1/2

`x` > +0

+0

+1/2

`a` > +0

+∞

+1/4

+∞

-∞

+3/4

+∞

`b` < +0

+1/2

+∞

-0

+1/2

+∞

+0

+1/2

+∞

`b` > +0

+1/2

+∞

+∞

+1/4

`a` > +0

QNAN

QNAN

`a` > +0

SNAN

QNAN

QNAN

`b` > +0

QNAN

SNAN

`x` > +0

QNAN

QNAN

QNAN

QNAN

QNAN

SNAN

QNAN

SNAN

QNAN

QNAN

SNAN

SNAN

QNAN

The atan2pi(a,b) function does not generate any errors.

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 1st input vector of size `n`.

b

The buffer `b` containing 2nd 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`.

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 1st input vector of size `n`.

b

Pointer `b` to the 2nd 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`.

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 atan2pican be found in the Intel® oneMKL installation directory, under:

```examples/sycl/vml/vatan2pi.cpp
```