[oct-scm] [oct-git]OCT: A portable Lisp implementation for quad-double precision floats branch master updated. e10e402d446339130042607357b0129b35a1faa7

[Raymond Toy]

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- Log -----------------------------------------------------------------
commit e10e402d446339130042607357b0129b35a1faa7
Author: Raymond Toy <toy.raymond at gmail.com>
Date:   Thu Mar 22 21:13:07 2012 -0700

    Correct the computation of s-exp-integral-e when v is an integer.  Add
    tests.

diff --git a/qd-gamma.lisp b/qd-gamma.lisp
index e5fc5f0..13f0bd9 100644
--- a/qd-gamma.lisp
+++ b/qd-gamma.lisp
@@ -501,16 +501,14 @@
 	  (- (* (/ (expt -z (- v 1))
 		   (gamma v))
 		(- (psi v) (log z)))
-	     (loop for k from 0 below n
-		   for term = 1 then (* term (/ -z k))
-		   for sum = (/ (- 1 v)) then (+ sum (/ term (+ k 1 -v)))
-		   when (< (abs term) (* (abs sum) eps))
-		     return sum)
-	     (loop for k from n
-		   for term = 1 then (* term (/ -z k))
-		   for sum = 0 then (+ sum (/ term (+ k 1 -v)))
-		   when (< (abs term) (* (abs sum) eps))
-		     return sum)))
+	     (loop for k from 0
+		       for term = 1 then (* term (/ -z k))
+		   for sum = (/ (- 1 v)) then (+ sum (let ((denom (+ k 1 (- n))))
+						       (if (zerop denom)
+							   0
+							   (/ term (+ k 1 -v)))))
+		       when (< (abs term) (* (abs sum) eps))
+			 return sum)))
 	(loop for k from 0
 	      for term = 1 then (* term (/ -z k))
 	      for sum = (/ (- 1 v)) then (+ sum (/ term (+ k 1 -v)))
diff --git a/rt-tests.lisp b/rt-tests.lisp
index fa6da81..173c528 100644
--- a/rt-tests.lisp
+++ b/rt-tests.lisp
@@ -1464,3 +1464,17 @@
 		    (expt x 4))))
       (check-accuracy 210.8 e true))
   nil)
+
+(rt:deftest expintegral-e.5d
+    (let* ((x .5d0)
+	   (e (exp-integral-e 2d0 x))
+	   (true #q0.3266438623245530177304015653336378358284946903290101))
+      (check-accuracy 51.2 e true))
+  nil)
+
+(rt:deftest expintegral-e.5q
+    (let* ((x #q.5)
+	   (e (exp-integral-e #q2 x))
+	   (true #q0.326643862324553017730401565333637835828494690329010198058745549181386569998611289568))
+      (check-accuracy 208.4 e true))
+  nil)
\ No newline at end of file

commit 1d9ec007bb4172eaccb8ca1db543c1218192cdb5
Author: Raymond Toy <toy.raymond at gmail.com>
Date:   Wed Mar 21 22:24:48 2012 -0700

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

diff --git a/qd-gamma.lisp b/qd-gamma.lisp
index d49acf8..e5fc5f0 100644
--- a/qd-gamma.lisp
+++ b/qd-gamma.lisp
@@ -527,7 +527,12 @@
   ;; for |arg(z)| < pi.
   ;;
   ;;
-  (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))
 	((>= (abs (phase z)) 3.1)
diff --git a/rt-tests.lisp b/rt-tests.lisp
index c5b6743..fa6da81 100644
--- a/rt-tests.lisp
+++ b/rt-tests.lisp
@@ -1447,4 +1447,20 @@
     (let* ((e (exp-integral-e 2 1d0))
 	   (true 0.14849550677592204791835999d0))
       (check-accuracy 47.5 e true))
-  nil)
\ No newline at end of file
+  nil)
+
+(rt:deftest expintegral-e.4d
+    (let* ((x .5d0)
+	   (e (exp-integral-e -2 x))
+	   (true (/ (* (exp (- x)) (+ (* x x x) (* 2 x x) (* 2 x)))
+		    (expt x 4))))
+      (check-accuracy 53 e true))
+  nil)
+
+(rt:deftest expintegral-e.4q
+    (let* ((x #q.5)
+	   (e (exp-integral-e -2 x))
+	   (true (/ (* (exp (- x)) (+ (* x x x) (* 2 x x) (* 2 x)))
+		    (expt x 4))))
+      (check-accuracy 210.8 e true))
+  nil)

-----------------------------------------------------------------------

Summary of changes:
 qd-gamma.lisp |   25 ++++++++++++++-----------
 rt-tests.lisp |   30 ++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+), 11 deletions(-)


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OCT:  A portable Lisp implementation for quad-double precision floats