WHILE	Repeat statements an indefinite number of times.
 	The general form of a WHILE statement is:
  
  	   WHILE variable, statement, ..., statement, END
  
  	The statements are executed while the variable has all
  	non-zero elements. The variable is usually the result of
  	expr rop expr where rop is ==, <, >, <=, >=, or ~=.
  	For example (assuming A already defined):
  
  	        E = 0*A; F = E + EYE(E); N = 1;
  	        WHILE NORM(E+F-E,1) > 0,
  	           E = E + F;
  	           F = A*F/N;
  	           N = N + 1;
  	        END