diff options
Diffstat (limited to 'src/approx/derivative.lisp')
| -rw-r--r-- | src/approx/derivative.lisp | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/src/approx/derivative.lisp b/src/approx/derivative.lisp index 02fcb4c..8aa171a 100644 --- a/src/approx/derivative.lisp +++ b/src/approx/derivative.lisp @@ -1,9 +1,17 @@ (in-package :lizfcm.approx) -(defun derivative-at (f x &optional (delta 0.01)) +(defun central-derivative-at (f x &optional (delta 0.01)) (let* ((x2 (+ x delta)) (x1 (- x delta)) (y2 (apply f (list x2))) (y1 (apply f (list x1)))) (/ (- y2 y1) (- x2 x1)))) + +(defun fwd-derivative-at (f x &optional (delta 0.01)) + (let* ((x2 (+ x delta)) + (x1 x) + (y2 (apply f (list x2))) + (y1 (apply f (list x1)))) + (/ (- y2 y1) + (- x2 x1)))) |