#2507 Strange non-evaluation of integral

None
closed
nobody
5
2015-11-07
2012-11-28
kcrisman
No

Originally reported at http://ask.sagemath.org/question/2027/why-does-this-not-integrate

Maxima 5.28.0 http://maxima.sourceforge.net
using Lisp SBCL 1.0.55.0-abb03f9
Distributed under the GNU Public License. See the file COPYING.
Dedicated to the memory of William Schelter.
The function bug_report() provides bug reporting information.
(%i1) display2d:false;

(%o1) false
(%i2) assume(n>0);

(%o2) [n > 0]
(%i3) integrate(1/sqrt(1+x^2*n),x,1,2);

(%o3) asinh(2*sqrt(n))/sqrt(n)-asinh(sqrt(n))/sqrt(n)
(%i4) integrate(1/sqrt(1+x^2/n),x,1,2);

(%o4) 'integrate(1/sqrt(x^2/n+1),x,1,2)

But shouldn't these really be the same if n is a constant? Maybe we're missing something.

Discussion

  • kcrisman

    kcrisman - 2012-11-28

    Also,

    (%i1) integrate(1/sqrt(1+x^2/n),x,1,2);
    Is n positive or negative?

    p;
    2 1
    (%o1) asinh(-------) sqrt(n) - asinh(-------) sqrt(n)
    sqrt(n) sqrt(n)

    So that is weird that it does it interactively, but not if one assumes n>0.

     
  • Robert Dodier

    Robert Dodier - 2013-08-01
    • labels: --> Lisp Core - Integration
    • Group: --> None
     
  • Kris Katterjohn

    Kris Katterjohn - 2015-11-07

    This appears to have been fixed at some point after v5.28. I've added a test in commit [819012].

    I'm closing this ticket.

     

    Related

    Commit: [819012]

  • Kris Katterjohn

    Kris Katterjohn - 2015-11-07
    • status: open --> closed
     

Log in to post a comment.

Get latest updates about Open Source Projects, Conferences and News.

Sign up for the SourceForge newsletter:





No, thanks