v?Atan

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 4/28/2026

Version

Public

v?Atan

vsAtan vdAtan vcAtan vzAtan vmsAtan vmdAtan vmcAtan vmzAtan Computes inverse tangent of vector elements.

Syntax

call vsatan ( n , a , y )

call vsatani(n, a, inca, y, incy)

call vmsatan ( n , a , y , mode )

call vmsatani(n, a, inca, y, incy, mode)

call vdatan ( n , a , y )

call vdatani(n, a, inca, y, incy)

call vmdatan ( n , a , y , mode )

call vmdatani(n, a, inca, y, incy, mode)

call vcatan ( n , a , y )

call vcatani(n, a, inca, y, incy)

call vmcatan ( n , a , y , mode )

call vmcatani(n, a, inca, y, incy, mode)

call vzatan ( n , a , y )

call vzatani(n, a, inca, y, incy)

call vmzatan ( n , a , y , mode )

call vmzatani(n, a, inca, y, incy, mode)

Include Files

mkl_vml.f90

Input Parameters

Name	Type	Description
`n`	INTEGER , INTENT(IN)	Specifies the number of elements to be calculated.
`a`	Fortran 77: DOUBLE PRECISION for `vdatan` , `vmdatan`Fortran 77: COMPLEX for `vcatan` , `vmcatan`Fortran 77: DOUBLE COMPLEX for `vzatan` , `vmzatan`Fortran 90: REAL , INTENT(IN) for `vsatan` , `vmsatan`Fortran 90: DOUBLE PRECISION , INTENT(IN) for `vdatan` , `vmdatan`Fortran 90: COMPLEX , INTENT(IN) for `vcatan` , `vmcatan`Fortran 90: DOUBLE COMPLEX , INTENT(IN) for `vzatan` , `vmzatan`	Array that specifies the input vector `a` .
`inca` , `incy`	INTEGER, INTENT(IN)	Specifies increments for the elements of `a` and `y` .
`mode`		Overrides global VM mode setting for this function call. See vmlSetMode (Sets a new mode for VM functions according to the mode parameter and stores the previous VM mode to oldmode.) for possible values and their description.

Output Parameters

Name	Type	Description
`y`	Fortran 77: DOUBLE PRECISION for `vdatan` , `vmdatan`Fortran 77: COMPLEX for `vcatan` , `vmcatan`Fortran 77: DOUBLE COMPLEX for `vzatan` , `vmzatan`Fortran 90: REAL , INTENT(OUT) for `vsatan` , `vmsatan`Fortran 90: DOUBLE PRECISION , INTENT(OUT) for `vdatan` , `vmdatan`Fortran 90: COMPLEX , INTENT(OUT) for `vcatan` , `vmcatan`Fortran 90: DOUBLE COMPLEX , INTENT(OUT) for `vzatan` , `vmzatan`	Array that specifies the output vector `y` .

Description

The v?Atan function computes inverse tangent of vector elements.

Special Values for Real Function v?Atan(x)

Argument	Result	Exception
+0	+0
-0	-0
∞	`π` /2
∞	`π` /2
QNAN	QNAN
SNAN	QNAN	INVALID

Specifications for special values of the complex functions are defined according to the following formula

\(Atan(z) = -i*Atanh(i*z)\) .

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

v?Atan

Syntax

Include Files

Input Parameters

Output Parameters

Description