[Maxima-commits] [git] Maxima CAS branch master updated. branch-5_49-base-491-g06f26693d

[dgildea <dg...@us...>]

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- Log -----------------------------------------------------------------
commit 06f26693d2a59da6bae8c4c701c9532ec1884360
Author: Dan Gildea <dgildea>
Date:   Thu May 7 20:45:26 2026 -0400

    powerseries for expintegral_ei(x) near zero
    
    Fixes #4730 ei-asymptotic-expansion

diff --git a/src/expintegral.lisp b/src/expintegral.lisp
index aae55b342..4bd55fae6 100644
--- a/src/expintegral.lisp
+++ b/src/expintegral.lisp
@@ -831,6 +831,15 @@
 		 (m* `((mfactorial) ,k)
 		     (m^ z (m- k)))))))
 
+;; computes first pw terms of powerseries expansion of expintegral_ei(z)
+;; DLMF 6.6.1			for limits as z -> 0
+(defun ei-powerseries (pw z)
+  (m+ '$%gamma
+      (take '(%log) z)
+      (m+l (loop for k from 1 to pw collect
+		 (m// (m^ z k)
+		      (m* k `((mfactorial) ,k)))))))
+
 
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
diff --git a/src/limit.lisp b/src/limit.lisp
index eee165e00..2527d8cd2 100644
--- a/src/limit.lisp
+++ b/src/limit.lisp
@@ -1246,10 +1246,13 @@ ignoring dummy variables and array indices."
 	 (li-asymptotic-expansion (m- (car (subfunsubs e)) 1) 
 				   (car (subfunsubs e))
 				   (car (subfunargs e))))
-	((and (eq (caar e) '%expintegral_ei)
-	      (let ((arglim (limit (cadr e) var val 'think)))
-		(eq arglim '$inf)))
-	 (ei-asymptotic-expansion $lhospitallim (cadr e)))
+	((eq (caar e) '%expintegral_ei)
+	 (let ((arglim (limit (cadr e) var val 'think)))
+	   (cond ((eq arglim '$inf)
+		  (ei-asymptotic-expansion $lhospitallim (cadr e)))
+		 ((zerop2 arglim)
+		  (ei-powerseries $lhospitallim (cadr e)))
+		 (t e))))
 	((eq (caar e) '%gamma_incomplete) (gamma-incomplete-asymptotic e var val $lhospitallim))
 	(t e)))
 
diff --git a/src/testsuite.lisp b/src/testsuite.lisp
index d4102c990..4c4200b20 100644
--- a/src/testsuite.lisp
+++ b/src/testsuite.lisp
@@ -143,7 +143,7 @@
                          262 267 268 269 270 272
                          281 282 357 358))
          ((mlist simp) "rtest_limit_gruntz"
-          ((mlist simp) 20 25 28 29 30 37 39 86 96))
+          ((mlist simp) 20 25 28 29 30 37 39 86))
 
          ((mlist simp) "rtest_limit_wester"
           ((mlist simp) 12 13))

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

Summary of changes:
 src/expintegral.lisp |  9 +++++++++
 src/limit.lisp       | 11 +++++++----
 src/testsuite.lisp   |  2 +-
 3 files changed, 17 insertions(+), 5 deletions(-)


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