In mathematics, the sign function or signum function (from signum, Latin for "sign") is a function that has the value −1, +1 or 0 according to whether the sign of a given real number is positive or negative, or the given number is itself zero. In mathematical notation the sign function is often represented as or . [1]

符號函數（Sign function，簡稱sgn）是一個邏輯函數，用以判斷實數的正負號。為避免和英文讀音相似的正弦函數（sine）混淆，它亦稱為Signum function。其定義為： = {: <: =: >

2024年8月2日 · Signum Function is an important function in mathematics that helps us to know the sign of a real number. It is usually expressed as a function of a variable and denoted either by f (x) or by sgn (x). It may also be written as a sign (x).

2016年6月9日 · On page 17, on equation (2.3.11) in the equation, a function sgn is used. What is sgn? To put it into context, in the book it says hn = h n = sgn (n)[(n − 1) + i] (n) [(n − 1) + i] The reason for abbreviation is a little clearer when calling it the signum function. sgn(x) =⎧⎩⎨1 0 −1 x> 0 x = 0 x <0. sgn (x) = {1 x> 0 0 x = 0 − 1 x <0.

已知函数 signFunc(x) 将会根据 x 的正负返回特定值：如果 x 是正数，返回 1 。如果 x 是负数，返回 -1 。 如果 x 是负数，返回 -1 。 如果 x 是等于 0 ，返回 0 。

2023年9月25日 · The sign function, also known as the signum function (from signum, Latin for "sign"), is a mathematical function that yields the sign of a real integer. The sign function is frequently expressed in mathematical notation as sgn (x).

2025年3月5日 · The sign of a real number, also called sgn or signum, is -1 for a negative number (i.e., one with a minus sign "-"), 0 for the number zero, or +1 for a positive number (i.e., one with a plus sign "+").

2024年4月11日 · SGN函数，全称为Sign Function，即符号函数，是一种在数学和工程领域广泛应用的基础函数。 本文将详细介绍SGN函数的定义、特性以及其在不同领域的使用场景。

2024年4月28日 · 在数学分析中，sgn函数常用于刻画函数的增减性。 例如，一个函数f(x)在x点的单调性可以通过f'(x)的sgn值来判断。 如果sgn(f'(x)) = 1，那么f(x)在该点单调递增；如果sgn(f'(x)) = -1，则单调递减。

What Is Signum Function? The signum function simply gives the sign for the given values of x. For x value greater than zero, the value of the output is +1, for x value lesser than zero, the value of the output is -1, and for x value equal to zero, the output is equal to zero.