CLEARRULES _ _ _ _ _ _ _ _ _ _ _ _ command

syntax:

The operator clearrules is used to remove previously defined rule lists from the system. <list> can be an exp licit rule list, or evaluate to a rule list.

examples:

trig1 := {cos(~x)*cos(~y) => (cos(x+y)+cos(x-y))/2,
          cos(~x)*sin(~y) => (sin(x+y)-sin(x-y))/2,
          sin(~x)*sin(~y) => (cos(x-y)-cos(x+y))/2,
          cos(~x)^2       => (1+cos(2*x))/2,
          sin(~x)^2       => (1-cos(2*x))/2}$ 

let trig1;
cos(a)*cos(b); 

  COS(A - B) + COS(A + B)
  ----------------------- 
             2


clearrules trig1;
cos(a)*cos(b); 

  COS(A)*COS(B)