v?logb

Compute the element-wise exponent of input vector x and return the result as a floating-point number.

Interface Definition

C interface:

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

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

Parameters

Parameter	Type	Description	Input/Output
len	Integer	Number of elements in the input vector. If len ≤ 0, an invalid parameter error is reported and the function returns.	Input
src	Single-precision floating-point type for vslogb Double-precision floating-point type for vdlogb	Input vector src with length len. If the pointer is null, a null pointer error is reported and the function returns.	Input
dst	Single-precision floating-point type for vslogb Double-precision floating-point type for vdlogb	Output vector dst with length len. If the pointer is null, a null pointer error is reported and the function returns.	Output

Parameter

Type

Description

Input/Output

len

Integer

Number of elements in the input vector.

If len ≤ 0, an invalid parameter error is reported and the function returns.

Input

src

Single-precision floating-point type for vslogb
Double-precision floating-point type for vdlogb

Input vector src with length len.

If the pointer is null, a null pointer error is reported and the function returns.

Input

dst

Single-precision floating-point type for vslogb
Double-precision floating-point type for vdlogb

Output vector dst with length len.

If the pointer is null, a null pointer error is reported and the function returns.

Output

Return Value

Each operation value returns its floating-point exponent value y. For vslogb, y ∈ [-149, 127]. For vdlogb, y ∈ [-1074, 1023].
For other special values, see the following table.
Input Value (src)

Output Value (dst)

±inf

+inf

±0

-inf

nan

nan

Input Value (src)	Output Value (dst)
±inf	+inf
±0	-inf
nan	nan

Dependencies

C: "kvml.h"

Examples

C interface:

    #define N 4
    const float src[N] = {73.2f, 8.0f, +INFINITY, +0.0f};
    float dst[N] = {0};

    vslogb(N, src, dst);
    printFArr("input1:", N, src);
    printFArr("output:", N, dst);

    /** 
     *  input1:  73.200    8.000      inf    0.000
     *  output:   6.000    3.000      inf     -inf 
     * 
     */

Parent topic: Function Syntax