This commit is contained in:
Thomas Baruchel 2022-10-04 15:49:52 +02:00
parent 40fc24500d
commit dab88dbdba
1 changed files with 35 additions and 0 deletions

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thiele.lisp Normal file
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; Thiele's interpolation formula
; ==============================
(defun $thiele (u v)
(loop for rh on
(loop for w on (cdr u) ; we build rho with axes transposed
; first, building column 1 and 2
for r = (list
(loop for a on u
for b on v
while (cdr a)
collect (div (sub (car a) (cadr a))
(sub (car b) (cadr b)))) v)
; then building starting from column 3
then (cons
(loop for a1 in u
for a2 in w
for y1 on (car r)
for y2 in (cdr (cadr r))
collect (add (div (sub a1 a2)
(sub (car y1) (cadr y1)))
y2)) r)
; finally get the row 1
; finally (return (loop for i in r ; i is already a 1-list
; for j = i then (cons (car i) j)
; finally (return j))))
finally (return (nreverse (mapcar #'car r))))
for k in (cdr u)
with a = 0
do (setf a (add a (div (sub 'x k)
(sub (caddr rh) (car rh)))))
finally (return (add (car v)
(div (sub 'x (car u))
(sub (cadr rh) a))))))