Re: how to speed up some lisp code?

From: Joe Marshall (jrm_at_ccs.neu.edu)
Date: 02/20/04

  • Next message: Joe Marshall: "Re: how to speed up some lisp code?" 
    Date: Fri, 20 Feb 2004 15:15:20 -0500

    John H Palmieri <palmieri@math.washington.edu> writes:

    >> (defun lex-less-than (left right)
    >> (and (not (eq left right)) ; short circuit EQ lists
    >> (consp right) ; right must be at least as long as left
    >> (or (not (consp left)) ; either left is shorter
    >> (< (car left) (car right)) ; the first element is smaller
    >> (and (= (car left) (car right)) ; the first elements are same
    >> (lex-less-than (cdr left) (cdr right))))))
    >
    > I think I made a mistake when coding this; I actually can't think of a
    > time when I need to compare monomials of different lengths. So I
    > could probably simplify this more. Anyway: I don't think eq is the
    > right thing to use: (eq '(1 2 3) '(1 2 3)) is nil, so it probably
    > won't save any time.

    (eq '(1 2 3) '(1 2 3)) may be nil, but you use this function in many
    places, not just for user input.

    > Does equal traverse the lists, or is it efficient enough to use as a
    > replacement here?

    EQUAL will traverse the entire list, you definitely don't want that
    here.

  • Next message: Joe Marshall: "Re: how to speed up some lisp code?"

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