Would an expression which uses the sign (signum) function be considered a closed expression?

[sly stratus]

I have written an expression in my homework which contains the sign function, and I wonder if it is appropriate for me to say that it is "closed." Wikipedia states that a closed expression can contain "certain well-known operations (e.g., + − × ÷), and functions (e.g., nth root, exponent, logarithm, trigonometric functions, and inverse hyperbolic functions), but usually no limit, differentiation, or integration." Would this typically include the sign function?

[gray sable]

if it's not used on a zero, you can make it from elementary functions afaik

otherwise maybe not

[solemn copper]

I think you can convincingly argue that a piecewise function of two closed form expressions is still a closed

but i think in general it can depend on what different people consider a closed form expression

[sly stratus]

thank you

.close