Changeset 015558a3df8fae2686c7b6e2f049da3f4b1a2cd8

Timestamp:

04/07/12 23:28:08 (14 months ago)

Author:

Raymond Toy <toy.raymond@…>

Children:

c86217a5f7191f1a29566d6ee24cb57344dd546d

Parents:

a5a4c7acd95d1946e7cf426f9a927a918c9e2afc

git-committer:

Raymond Toy <toy.raymond@…> (04/07/12 23:28:08)

Message:

Fix a divide by zero error in s-exp-integral-e for v = 1. We need to
skip the first term in the series.

Files:

• qd-gamma.lisp (modified) (2 diffs)

qd-gamma.lisp

@@ -258 +258 @@
 ;; result is greater than 1.
 #+nil
-(defun erf (z)
+(defun cf-erf (z)
   (let* ((z2 (* z z))
          (twoz2 (* 2 z2)))
@@ -505 +505 @@
              (loop for k from 0
                    for term = 1 then (* term (/ -z k))
-                   for sum = (/ (- 1 v)) then (+ sum (let ((denom (- k n-1)))
-                                                       (if (zerop denom)
-                                                           0
-                                                           (/ term denom))))
+                   for sum = (if (zerop n-1)
+                                 0
+                                 (/ (- 1 v)))
+                     then (+ sum (let ((denom (- k n-1)))
+                                   (if (zerop denom)
+                                       0
+                                       (/ term denom))))
                    when (< (abs term) (* (abs sum) eps))
                      return sum)))