Primality by trial division: Difference between revisions

Line 1,596:

=={{header|Emacs Lisp}}==

Use <tt>cl.el</tt> library.

<lang lisp>(defun prime (a)

(not (or (< a 2)

(loop for x from 2 to (sqrt a)

(cl-loop for x from 2 to (sqrt a)

when (zerop (% a x))

return t))))</lang>

More concise, a little bit faster:

<lang lisp>(defun prime2 (a)

(and (> a 1)

(loop for x from 2 to (sqrt a)

(cl-loop for x from 2 to (sqrt a)

never (zerop (% a x)))))</lang>

A little bit faster:

<lang lisp>(defun prime3 (a)

(and (> a 1)

(or (= a 2) (oddp a))

(or (= a 2) (cl-oddp a))

(loop for x from 3 to (sqrt a) by 2

(cl-loop for x from 3 to (sqrt a) by 2

never (zerop (% a x)))))</lang>

More than 2 times faster, than the previous, doesn't use <tt>loop</tt> macro:

<lang lisp>(defun prime4 (a)

(not (or (< a 2)

(some (lambda (x) (zerop (% a x))) (number-sequence 2 (sqrt a))))))</lang>

(cl-some (lambda (x) (zerop (% a x))) (number-sequence 2 (sqrt a))))))</lang>

Almost 2 times faster, than the previous:

<lang lisp>(defun prime5 (a)

(not (or (< a 2)

(and (/= a 2) (evenp a))

(and (/= a 2) (cl-evenp a))

(some (lambda (x) (zerop (% a x))) (number-sequence 3 (sqrt a) 2)))))</lang>

(cl-some (lambda (x) (zerop (% a x))) (number-sequence 3 (sqrt a) 2)))))</lang>

=={{header|Erlang}}==