v?Acos

Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

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ID 766686

Date 10/15/2026

Version

Public

v?Acos

vsAcos vdAcos vcAcos vzAcos vmsAcos vmdAcos vmcAcos vmzAcos Computes inverse cosine of vector elements.

Syntax

call vsacos(n, a, y)
call vsacosi(n, a, inca, y, incy)
call vmsacos(n, a, y, mode)
call vmsacosi(n, a, inca, y, incy, mode)
call vdacos(n, a, y)
call vdacosi(n, a, inca, y, incy)
call vmdacos(n, a, y, mode)
call vmdacosi(n, a, inca, y, incy, mode)
call vcacos(n, a, y)
call vcacosi(n, a, inca, y, incy)
call vmcacos(n, a, y, mode)
call vmcacosi(n, a, inca, y, incy, mode)
call vzacos(n, a, y)
call vzacosi(n, a, inca, y, incy)
call vmzacos(n, a, y, mode)
call vmzacosi(n, a, inca, y, incy, mode)

Include Files

mkl_vml.f90

Input Parameters

Name	Type	Description
`n`		Specifies the number of elements to be calculated.
`a`	Fortran 77: DOUBLE PRECISION for `vdacos` , `vmdacos`Fortran 77: COMPLEX for `vcacos` , `vmcacos`Fortran 77: DOUBLE COMPLEX for `vzacos` , `vmzacos`Fortran 90: REAL , INTENT(IN) for `vsacos` , `vmsacos`Fortran 90: DOUBLE PRECISION , INTENT(IN) for `vdacos` , `vmdacos`Fortran 90: COMPLEX , INTENT(IN) for `vcacos` , `vmcacos`Fortran 90: DOUBLE COMPLEX , INTENT(IN) for `vzacos` , `vmzacos`	Array that specifies the input vector `a` .
`inca` , `incy`	INTEGER, INTENT(IN)	Specifies increments for the elements of `a` and `y` .
`mode`	INTEGER(KIND=8) , INTENT(IN)	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 `vdacos` , `vmdacos`Fortran 77: COMPLEX for `vcacos` , `vmcacos`Fortran 77: DOUBLE COMPLEX for `vzacos` , `vmzacos`Fortran 90: REAL , INTENT(OUT) for `vsacos` , `vmsacos`Fortran 90: DOUBLE PRECISION , INTENT(OUT) for `vdacos` , `vmdacos`Fortran 90: COMPLEX , INTENT(OUT) for `vcacos` , `vmcacos`Fortran 90: DOUBLE COMPLEX , INTENT(OUT) for `vzacos` , `vmzacos`	Array that specifies the output vector `y` .

Description

The v?Acos function computes inverse cosine of vector elements.

Special Values for Real Function v?Acos(x)

Argument	Result	VM Error Status	Exception
+0	`π` /2
-0	`π` /2
+1	+0
-1	`π`
`\(\|X\| > 1\)`	QNAN	VML_STATUS_ERRDOM	INVALID
∞	QNAN	VML_STATUS_ERRDOM	INVALID
∞	QNAN	VML_STATUS_ERRDOM	INVALID
QNAN	QNAN
SNAN	QNAN		INVALID

See Special Value Notations for the conventions used in the table below.

Special Values for Complex Function v?Acos(z)

RE(z) i · IM(z)	∞	-X	-0	+0	+X	∞	NAN
+i · ∞	+3 · `π` /4-i · ∞	`π` /2-i · ∞	`π` /2-i · ∞	`π` /2-i · ∞	`π` /2-i · ∞	`π` /4-i · ∞	QNAN-i · ∞
+i · Y	`π` -i · ∞					+0-i · ∞	QNAN+i · QNAN
+i · 0	`π` -i · ∞		`π` /2-i · 0	`π` /2-i · 0		+0-i · ∞	QNAN+i · QNAN
-i · 0	`π` +i · ∞		`π` /2+i · 0	`π` /2+i · 0		+0+i · ∞	QNAN+i · QNAN
-i · Y	`π` +i · ∞					+0+i · ∞	QNAN+i · QNAN
-i · ∞	+3 `π` /4+i · ∞	`π` /2+i · ∞	`π` /2+i · ∞	`π` /2+i · ∞	`π` /2+i · ∞	`π` /4+i · ∞	QNAN+i · ∞
+i · NAN	QNAN+i · ∞	QNAN+i · QNAN	`π` /2+i · QNAN	`π` /2+i · QNAN	QNAN+i · QNAN	QNAN+i · ∞	QNAN+i · QNAN

Notes:

raises INVALID exception when real or imaginary part of the argument is SNAN
\(Acos(CONJ(z))=CONJ(Acos(z))\) .

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Developer Reference for Intel® oneAPI Math Kernel Library for Fortran

v?Acos

Syntax

Include Files

Input Parameters

Output Parameters

Description