v?Atan

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 10/15/2026

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