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v?atan

Compute the arc tangent of vector elements.

Interface Definition

C interface:

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

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

Fortran interface:

CALL VSATAN(LEN, SRC, DST);

CALL VDATAN(LEN, SRC, 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
  • For vsatan, src is of the single-precision floating-point type.
  • For vdatan, src is of the double-precision floating-point type.

Input vector src with length len.

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

Input

dst
  • For vsatan, dst is of the single-precision floating-point type.
  • For vdatan, dst is of the double-precision floating-point type.

Output vector dst with length len.

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

Output

Return Value

  1. The unique angle whose tangent value is x at (–π/2, π/2) is returned. The value range is (–π/2, +π/2).
  2. If the input is +0, the return value is +0.
  3. If the input is -0, the return value is -0.
  4. If the input is +∞, the return value is +π/2.
  5. If the input is -∞, the return value is -π/2.
  6. If the input is NaN, the return value is NaN.

Dependencies

C: "kvml.h"

Fortran: "kvml.f03"

Examples

C interface:

    int i, len = 4; 
    float src[len] = [0.0f, 2.0f, inf, nan]; 
    float* dst = (float*)malloc(sizeof(float) * len); 
    if (dst == NULL) { 
        printf("Malloc Failed!\n"); 
        return 0; 
    } 
    vsatan(len, src, dst); 
    /** 
     *  Output dst: 
     *     0.0  1.107148766517639  1.570796370506287  nan 
     * 
     */

Fortran interface:

    INTEGER :: LEN = 4 
    REAL(4) SRC(4)  
    REAL(4) DST(4) 
    DATA SRC /1, 2, 3, 4/ 
    CALL VSATAN(LEN, SRC, DST) 
    !  
    ! OUTPUT DST: 
    !     0.785398185, 1.10714877, 1.24904573, 1.32581770 
    !