Changeset 1d9ec007bb4172eaccb8ca1db543c1218192cdb5 for qd-gamma.lisp

Timestamp:

03/21/12 22:24:48 (14 months ago)

Author:

Raymond Toy <toy.raymond@…>

Children:

e10e402d446339130042607357b0129b35a1faa7

Parents:

4b332ed2140e56c6fcaa689e6b8a48be36c988f6

git-committer:

Raymond Toy <toy.raymond@…> (03/21/12 22:24:48)

Message:

Handle the case of negative v in exp-integral-e(v, z). Add tests.

Files:

• qd-gamma.lisp (modified) (1 diff)

qd-gamma.lisp

@@ -528 +528 @@
   ;;
   ;;
-  (cond ((< (abs z) 1)
+  (cond ((and (realp v) (minusp v))
+         ;; E(-v, z) = z^(-v-1)*incomplete_gamma_tail(v+1,z)
+         (let ((-v (- v)))
+           (* (expt z (- v 1))
+              (incomplete-gamma-tail (+ -v 1) z))))
+        ((< (abs z) 1)
          ;; Use series for small z
          (s-exp-integral-e v z))