diff options
Diffstat (limited to 'gtwiwtg.lisp')
| -rw-r--r-- | gtwiwtg.lisp | 51 |
1 files changed, 1 insertions, 50 deletions
diff --git a/gtwiwtg.lisp b/gtwiwtg.lisp index fe0f679..5938065 100644 --- a/gtwiwtg.lisp +++ b/gtwiwtg.lisp @@ -592,7 +592,7 @@ Example: a usless calculation ((x y) (zip! (times 10) (range :by -1))) (sqrt (+ acc (* x y)))) -#C(0.4498776 9.987898) + #C(0.444279 8.986663) Example: building data @@ -684,52 +684,3 @@ is minimal among the values of GEN. VALUE is the value of (FUNCALL FN X)" am)))) -;;; EXAMPLES - - -;; permutations - -(defun fill-and-insert (idx elem vec buffer) - "A Utility function that inserts ELEM at IDX into BUFFER. For every -other space in BUFFER, the lements of VEC are inserted in order. - -Implicity expects (= (LENGTH BUFFER) (1+ (LENGTH VEC))) - -Not meant for general use. just a utility used by THREAD-THROUGH" - (loop :for i :below (length buffer) - :when (= i idx) :do (setf (aref buffer idx) elem) - :when (< i idx) :do (setf (aref buffer i) - (aref vec i)) - :when (> i idx) :do (setf (aref buffer i) - (aref vec (1- i)))) ) - -(defun thread-through (elem vec) - (let ((buffer (concatenate 'vector vec (list elem)))) ;; reusable buffer - (map! (lambda (idx) - (fill-and-insert idx elem vec buffer) - buffer) - (range :from 0 :to (length vec))))) - - -(defun perms (vec) - (if (= 1 (length vec)) (seq (list vec)) - (let ((elem (elt vec 0)) - (subperms (perms (make-array (1- (length vec)) - :displaced-to vec - :displaced-index-offset 1 - :element-type (array-element-type vec))))) - (inflate! (lambda (subperm) (thread-through elem subperm)) subperms)))) - - -;; primes - -(defun prime-p (n) - (loop - :for x :from 2 :upto (sqrt n) - :when (zerop (mod n x)) :do (return nil) - :finally (return t))) - -(defun all-primes () - (filter! #'prime-p (range :from 1))) - - |