[texhax] signum(x) function?

[doug waud]

Hi

Here's another exercise in blind leading blind :-)

John Wheeler wrote:
> Can someone tell me if there is a LaTeX or AMSLaTeX function for
> signum(x), the algebraic sign of x?  I expected \sgn{x}, but that gives an
> error.

I looked in the TeXbook and did not find signum there. However, I note 
that cousins, like sup, det, log are defined simply as
	\def\det{\mathop{\rm det}}
so I would suggest simply defining sup the same way and then it will 
match all the others.

There is a list of similar functions on the second page of Chapter 18, 
Fine points of mathematics typing, and appendix B gives the code I am 
stealing above.

doug