v?Acos

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 4/28/2026

Version

Public

v?Acos

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

Syntax

vhAcos ( n , a , y ) ;

vhAcosI(n, a, inca, y, incy);

vmhAcos ( n , a , y , mode ) ;

vmhAcosI(n, a, inca, y, incy, mode);

vsAcos ( n , a , y ) ;

vsAcosI(n, a, inca, y, incy);

vmsAcos ( n , a , y , mode ) ;

vmsAcosI(n, a, inca, y, incy, mode);

vdAcos ( n , a , y ) ;

vdAcosI(n, a, inca, y, incy);

vmdAcos ( n , a , y , mode ) ;

vmdAcosI(n, a, inca, y, incy, mode);

vcAcos ( n , a , y ) ;

vcAcosI(n, a, inca, y, incy);

vmcAcos ( n , a , y , mode ) ;

vmcAcosI(n, a, inca, y, incy, mode);

vzAcos ( n , a , y ) ;

vzAcosI(n, a, inca, y, incy);

vmzAcos ( n , a , y , mode ) ;

vmzAcosI(n, a, inca, y, incy, mode);

Include Files

mkl.h

Input Parameters

Name	Type	Description
`n`	const int	Specifies the number of elements to be calculated.
`a`	const _Float16* for `vhAcos` , `vmhAcos` const float* for `vsAcos` , `vmsAcos` const double* for `vdAcos` , `vmdAcos` const MKL_Complex8* for `vcAcos` , `vmcAcos` const MKL_Complex16* for `vzAcos` , `vmzAcos`	Pointer to an array that contains the input vector `a` .
`inca` , `incy`	const MKL_INT	Specifies increments for the elements of `a` and `y` .
`mode`	const MKL_INT64	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`	_Float16* for `vhAcos` , `vmhAcos` float* for `vsAcos` , `vmsAcos` double* for `vdAcos` , `vmdAcos` MKL_Complex8* for `vcAcos` , `vmcAcos` MKL_Complex16* for `vzAcos` , `vmzAcos`	Pointer to an array that contains 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 C

v?Acos

Syntax

Include Files

Input Parameters

Output Parameters

Description