archive/share/trash/sqdnst.mcs

   1 /* -*- Mode: MACSYMA -*- */
   2
   3 SQRTDENEST(A):=
   4   BLOCK([DISCR,MAX,MIN],
   5         SUBST("^" = LAMBDA([A,B],
   6                        IF EVENP(DENOM(B)) AND NOT ATOM(A) AND INPART(A,0) = "+"
   7                                           AND (MAX:MAX(FIRST(A),REST(A)),
   8                                                MIN:A-MAX,
   9                                                NUMBERP(DISCR:SQRT(1-(MIN/MAX)^2)))
  10                           THEN (SQRT(MAX*(1+DISCR)/2)+SIGNUM(MIN)*SQRT(MAX*(1-DISCR)/2))^(2*B)
  11                           ELSE A^B),
  12               A));