/*  Demonstration of pattern-matching  */
/*  remove the terms "sin(5*x)", "sin(6*x)", ... from an expression  */

  /*  anonymous function:  Replace term, if symbol "q" is 4 < q  */
matchdeclare(q, lambda([x], 4<x))$
  /*  name as "r1", rule replacing "sin(q*x)" with "0"  */
defrule(r1, sin(q*x), 0)$
  /*  apply rule "r1", repeatedly to each term in the expression  */
apply1(a*sin(x)+b*sin(2*x)+c*sin(5*x)+d*sin(6*x), r1);


  /* appended expression:  Replace term, if symbol "q" is 4 < (q)  */
matchdeclare(q, "<"(4))$  /*  "<"(4,q)  */
  /*  name as "r1", rule replacing "sin(q*x)" with "0"  */
defrule(r1, sin(q*x), 0)$
  /*  apply rule "r1", repeatedly to each term in the expression  */
apply1(a*sin(x)+b*sin(2*x)+c*sin(5*x)+d*sin(6*x), r1);


/*  Demonstration of pattern-matching  */
/*  rotate cartesian co-ordinates by 270 degrees  */

  /*  replace term if its symbols aren't expressions  */
matchdeclare([xxxx,yyyy], atom)$
  /*  use same symbols as MatchDeclare()  */
defrule(r1, [xxxx,yyyy], [yyyy,-xxxx])$
  /*  apply the rule  */
r1([5,3]);
makelist(r1(k), k, [[5,3], [6,2], [7,1]]);


  /*  display declared symbols  */
printprops(all, matchdeclare);