Editing Sign function (section)

== Basic properties ==
Any real number can be expressed as the product of its [[absolute value]] and its sign:
<math display="block"> x = |x| \sgn x\,.</math>

It follows that whenever <math>x</math> is not equal to 0 we have
<math display="block"> \sgn x = \frac{x}{|x|} = \frac{|x|}{x}\,.</math>

Similarly, for ''any'' real number <math>x</math>,
<math display="block"> |x| = x\sgn x\,. </math>
We can also be certain that:
<math display="block">\sgn (xy)=(\sgn x)(\sgn y)\,,</math>
and so
<math display="block">\sgn (x^n)=(\sgn x)^n\,.</math>