[Maxima-commits] Maxima, A Computer Algebra System branch, master, updated. 120f31e72216cbee3615e617b4570c271d83c9c6

[Dan G. <dg...@us...>]

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- Log -----------------------------------------------------------------
commit 120f31e72216cbee3615e617b4570c271d83c9c6
Author: Dan Gildea <dgildea>
Date:   Wed May 18 16:33:55 2011 -0400

    src/defint.lisp:
    o intcv: check which root gives inverse of new var of integration
      fixes Incorrect integral of log(1+a/(x*t)^2) - ID: 3291160
    
    src/limit.lisp:
    o add comment
    
    tests/rtestint.mac:
    o add integrate(log(1+7/(x^2)),x,1,inf);

diff --git a/src/defint.lisp b/src/defint.lisp
index b377ab2..2d250d1 100644
--- a/src/defint.lisp
+++ b/src/defint.lisp
@@ -335,6 +335,15 @@ in the interval of integration.")
 			  (t (intcv1 d ind nv))))
 		   (t ()))))))
 
+;; test whether fun2 is inverse of fun1 at val
+(defun test-inverse (fun1 var1 fun2 var2 val)
+  (let* ((out1 (let ((var var1))
+		 (no-err-sub val fun1)))
+	 (out2 (let ((var var2))
+		 (no-err-sub out1 fun2))))
+    (alike1 val out2)))
+
+;; integration change of variable
 (defun intcv (nv ind flag)
   (let ((d (bx**n+a nv))
 	(*roots ())  (*failures ())  ($breakup ()))
@@ -360,8 +369,14 @@ in the interval of integration.")
 		 (t
 		  (putprop 'yx t 'internal);; keep var from appearing in questions to user
 		  (solve (m+t 'yx (m*t -1 nv)) var 1.)
-		  (cond (*roots
-			 (setq d (caddar *roots))
+		  (cond ((setq d	;; look for root that is inverse of nv
+			       (do* ((roots *roots (cddr roots))
+				     (root (caddar roots) (caddar roots)))
+				    ((null root) nil)
+				    (if (test-inverse nv var root 'yx ll)
+					;; to do: check upper limit, 
+					;;        test for minf/inf
+					(return root))))
 			 (cond (flag (intcv2 d ind nv))
 			       (t (intcv1 d ind nv))))
 			(t ()))))))))
diff --git a/src/limit.lisp b/src/limit.lisp
index f2c1cc2..aa3eb16 100644
--- a/src/limit.lisp
+++ b/src/limit.lisp
@@ -232,8 +232,7 @@ It appears in LIMIT and DEFINT.......")
 
 	      (if ans
 		  (return (clean-limit-exp ans))
-                  (return (cons '(%limit) args)))))
-;      		  (return (nounlimit exp var val)))))
+                  (return (cons '(%limit) args)))))	;; failure: return nounform
       (restore-assumptions))))
 
 (defun clean-limit-exp (exp)
diff --git a/tests/rtestint.mac b/tests/rtestint.mac
index ead8ca3..6d8965f 100644
--- a/tests/rtestint.mac
+++ b/tests/rtestint.mac
@@ -1359,3 +1359,7 @@ integrate(%e^(-1/x^2),x,0,1);
 /* definite integration introduces xy variable - ID: 3292707 */
 integrate((log((2-x)/2)+log(2))/(1-x), x, 0, 1);
 'integrate((log((2-x)/2)+log(2))/(1-x), x, 0, 1);
+
+/* Incorrect integral of log(1+a/(x*t)^2) - ID: 3291160 */
+integrate(log(1+7/(x^2)),x,1,inf);
+(14*atan(sqrt(7))-sqrt(7)*log(8))/sqrt(7);

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

Summary of changes:
 src/defint.lisp    |   19 +++++++++++++++++--
 src/limit.lisp     |    3 +--
 tests/rtestint.mac |    4 ++++
 3 files changed, 22 insertions(+), 4 deletions(-)


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