RATIONAL _ _ _ _ _ _ _ _ _ _ _ _ switch

When rational is on, polynomial expressions with rational coefficients are produced.

examples:

x/2 + 3*y/4; 

  2*X + 3*Y
  --------- 
      4


(x**2 + 5*x + 17)/2; 

   2
  X  + 5*X + 17
  ------------- 
        2


on rational; 

x/2 + 3y/4; 

  1      3
  -*(X + -*Y) 
  2      2


(x**2 + 5*x + 17)/2; 

  1   2
  -*(X  + 5*X + 17)
  2

By using rational, polynomial expressions with rational coefficients can be used in some commands that expect polynomials. With rational off, such a polynomial becomes a rational expression, with denominator the least common multiple of the denominators of the rational number coefficients.