symmp

use it if you like.. i needed it as a subfuction for length-legato* ...

greetings

andré

(defun symmp (seq)
  (let ((seq2 (if (evenp (length seq))
                (list (filter-first  (/ (length seq) 2) seq)
                      (reverse (filter-last (/ (length seq) 2) seq)))
                (list (filter-first (/ (1- (length seq)) 2) seq) 
                      (reverse (filter-last (/ (1- (length seq)) 2) seq))))))

    (if (null (member 'nil (loop 
                             for i in (car seq2)
                             for j in (cadr seq2)
                             when (equal i j)
                             collect 'T else collect 'NIL)))
      't)))

  
(symmp '(-1 2 3 5 5 3 2 -1))
(symmp '(-1 2 3 5 7 5 3 2 -1))
(symmp '(-1 2 3 4 5 3 2 -1))


(symmp '(c4 d4 fs5 d4 c4))
(symmp '(c4 d4 fs5 d4 b4))

(symmp '(mf f mp mp f mf))
(symmp '(mf f f mp fff f mf))