funcs.lisp

khizha acl2 tasks

(defun natural (a)
    (and (integerp a) (> a 0))
)

(defun fib (x)
    (if (and (integerp x) (>= x 0))
        (if (< x 2)
            1
            (+ (fib (- x 1)) (fib (- x 2)))
        )
    nil
    )
)

(defun mygcd (a b)
    (if (and (natural a) (natural b))
        (/ a (numerator (/ a b)))
        nil
    )
)

(defun mylcm (a b)
    (if (and (natural a) (natural b))
        (/ (* a b) (mygcd a b))
        nil
    )
)

(defun d2b (a)
    (if (and (integerp a) (>= a 2))
        (append (d2b (floor a 2)) (list (mod a 2)))
        (list a)
    )
)

(defun myreverse (mylist)
    (if (true-listp mylist)
        (if (> (length mylist) 0)
            (append (myreverse (cdr mylist)) (list (car mylist)))
            '()
        )
        nil
    )
)