RosettaCodeData/Task/Gamma-function/Common-Lisp/gamma-function.lisp

27 lines
1.1 KiB
Common Lisp

; Taylor series coefficients
(defconstant tcoeff
'( 1.00000000000000000000 0.57721566490153286061 -0.65587807152025388108
-0.04200263503409523553 0.16653861138229148950 -0.04219773455554433675
-0.00962197152787697356 0.00721894324666309954 -0.00116516759185906511
-0.00021524167411495097 0.00012805028238811619 -0.00002013485478078824
-0.00000125049348214267 0.00000113302723198170 -0.00000020563384169776
0.00000000611609510448 0.00000000500200764447 -0.00000000118127457049
0.00000000010434267117 0.00000000000778226344 -0.00000000000369680562
0.00000000000051003703 -0.00000000000002058326 -0.00000000000000534812
0.00000000000000122678 -0.00000000000000011813 0.00000000000000000119
0.00000000000000000141 -0.00000000000000000023 0.00000000000000000002))
; number of coefficients
(defconstant numcoeff (length tcoeff))
(defun gamma (x)
(let ((y (- x 1.0))
(sum (nth (- numcoeff 1) tcoeff)))
(loop for i from (- numcoeff 2) downto 0 do
(setf sum (+ (* sum y) (nth i tcoeff))))
(/ 1.0 sum)))
(loop for i from 1 to 10
do (
format t "~12,10f~%" (gamma (/ i 3.0))))