v?acos

Interface Definition

C interface:

void vsacos(const int len, const float* src, float* dst);

void vdacos(const int len, const double* src, double* dst);

void vcacos(const int len, const float complex *src, float complex *dst);

void vzacos(const int len, const double complex *src, double complex *dst);

Parameters

Parameter	Type	Description	Input/Output
len	Integer	Number of elements in the input vector. If len ≤ 0, the system displays a message indicating that the value of len is invalid.	Input
src	Single-precision floating-point type for vsacos Double-precision floating-point type for vdacos Single-precision floating-point complex type for vcacos Double-precision floating-point complex type for vzacos	Input vector src with length len. If the pointer is null, the system prompts a null pointer error.	Input
dst	Single-precision floating-point type for vsacos Double-precision floating-point type for vdacos Single-precision floating-point complex type for vcacos Double-precision floating-point complex type for vzacos	Output vector dst with length len. If the pointer is null, the system prompts a null pointer error.	Output

Parameter

Type

Description

Input/Output

len

Integer

Number of elements in the input vector.

If len ≤ 0, the system displays a message indicating that the value of len is invalid.

Input

src

Single-precision floating-point type for vsacos
Double-precision floating-point type for vdacos
Single-precision floating-point complex type for vcacos
Double-precision floating-point complex type for vzacos

Input vector src with length len.

If the pointer is null, the system prompts a null pointer error.

Input

dst

Single-precision floating-point type for vsacos
Double-precision floating-point type for vdacos
Single-precision floating-point complex type for vcacos
Double-precision floating-point complex type for vzacos

Output vector dst with length len.

If the pointer is null, the system prompts a null pointer error.

Output

Return Value

The arccosine y of cosine x is returned. x ∈ [-1, +1]
For vsacos and vdacos, the special values are listed in the following table.
Input Value (src)

Output Value (dst)

±inf

nan

nan

nan

+1

+0

-1

+pi

|x|>1

nan

Input Value (src)	Output Value (dst)
±inf	nan
nan	nan
+1	+0
-1	+pi
\|x\|>1	nan

For vcacos and vzacos, the special values are listed in the following table.

Real Part of the Input (src.real)	Imaginary Part of the Input (src.imag)	Real Part of the Output (dst.real)	Imaginary Part of the Output (dst.imag)
0	0	π/2	0
0	0	π/2	0
0	inf	π/2	-inf
0	-inf	π/2	inf
0	snan	π/2	nan
0	-snan	π/2	nan
0	qnan	π/2	nan
0	-qnan	π/2	nan
0	0	π/2	0
0	0	π/2	0
0	inf	π/2	-inf
0	-inf	π/2	inf
0	snan	π/2	nan
0	-snan	π/2	nan
0	qnan	π/2	nan
0	-qnan	π/2	nan
inf	0	0	-inf
inf	0	0	inf
inf	inf	π/4	-inf
inf	-inf	π/4	inf
inf	snan	nan	-inf
inf	-snan	nan	-inf
inf	qnan	nan	-inf
inf	-qnan	nan	-inf
-inf	0	π	-inf
-inf	0	π	inf
-inf	inf	3*π/4	-inf
-inf	-inf	3*π/4	inf
-inf	snan	nan	-inf
-inf	-snan	nan	-inf
-inf	qnan	nan	-inf
-inf	-qnan	nan	-inf
snan	0	nan	nan
snan	0	nan	nan
snan	inf	nan	-inf
snan	-inf	nan	inf
snan	snan	nan	nan
snan	-snan	nan	nan
snan	qnan	nan	nan
snan	-qnan	nan	nan
-snan	0	nan	nan
-snan	0	nan	nan
-snan	inf	nan	-inf
-snan	-inf	nan	inf
-snan	snan	nan	nan
-snan	-snan	nan	nan
-snan	qnan	nan	nan
-snan	-qnan	nan	nan
qnan	0	nan	nan
qnan	0	nan	nan
qnan	inf	nan	-inf
qnan	-inf	nan	inf
qnan	snan	nan	nan
qnan	-snan	nan	nan
qnan	qnan	nan	nan
qnan	-qnan	nan	nan
-qnan	0	nan	nan
-qnan	0	nan	nan
-qnan	inf	nan	-inf
-qnan	-inf	nan	inf
-qnan	snan	nan	nan
-qnan	-snan	nan	nan
-qnan	qnan	nan	nan
-qnan	-qnan	nan	nan

Dependency

C: "kvml.h"

Example

C interface:

    int i, len = 4; 
    float src[4] = {0.0f, 2.0f, INFINITY, NAN}; 
    float* dst = (float*)malloc(sizeof(float) * len); 
    if (dst == NULL) { 
        printf("Malloc Failed!\n"); 
        return 0; 
    } 
    vsacos(len, src, dst);

    /** 
     *  Output dst: 
     *     1.570796 nan nan nan
     */

Parent topic: Function Syntax