Return zero if x==0 and $x/|x|$ otherwise (i.e., ±1 for real x).


In the Julia programming language, the function sign(x) returns zero if x is equal to zero, and x/|x| otherwise. It essentially returns ±1 for real x. Here are some examples of its usage:

  1. Determine the sign of a number:

    julia> sign(5)
    julia> sign(-3)

    This example shows how the sign function returns 1 for positive numbers and -1 for negative numbers.

  2. Handle zero input:

    julia> sign(0)

    When the input is zero, the sign function returns 0.

  3. Compute the sign of an array:

    julia> arr = [-2, 4, -6, 8];
    julia> sign.(arr)
    4-element Array{Int64,1}:

    By using the dot syntax (.), we can apply the sign function element-wise to an array.

Common mistake example:

julia> sign("Hello")
ERROR: MethodError: no method matching sign(::String)

In this example, the sign function is applied to a string, which is not a valid argument. The sign function is only applicable to numeric types. Make sure to pass appropriate numeric values to the sign function to avoid such errors.

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