.he 'SIGN''Page %'
.fo 'Steven Hardy''January 78'
SIGN	This function returns -1 if applied to a negative number, 0 if
applied to 0 and +1 if applied to a positive number.  It could be 
defined as:
 	: FUNCTION SIGN(NUM);
 	:	IF	NUM < 0
 	:	THEN	-1
 	:	ELSEIF	NUM = 0
 	:	THEN	0
 	:	ELSE	+1
 	:	CLOSE
 	: END;
.br
Thus
 	: SIGN(X) * X
.br
will always be positive (provided X is a number).
