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Sign function
From Mathematics Is A Science
Jump to navigationJump to search$$ f(x) = \begin{cases} -1 & \text{ if } x < 0 \\ 0 & \text{ if } x = 0 \\ 1 & \text{ if } x > 0 \end{cases} $$
Domain $f =(-\infty,\infty), f(0)= 0.$
