#2349 integrate(sin(x)^2/x,x,minf,inf) gives not zero

closed
5
2012-01-28
2012-01-28
No

ya@debian:~$ maxima
Maxima 5.26.0 http://maxima.sourceforge.net
using Lisp CLISP 2.48 (2009-07-28)
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) integrate(sin(x)^2/x,x,minf,inf);
Principal Value
log(- 1)
(%o1) - --------
2
(%i2)

sin(x)^2/x is odd function, so result of integration must be 0.

Discussion

  • Ted Woollett

    Ted Woollett - 2012-01-28

    5.25.1gcl gave correct value (0 by symmetry)
    (%i1) integrate(sin(x)^2/x,x,minf,inf);
    Principal Value
    (%o1) 0
    (%i2) build_info()$

    Maxima version: 5.25.1
    Maxima build date: 10:2 9/6/2011
    Host type: i686-pc-mingw32
    Lisp implementation type: GNU Common Lisp (GCL)
    Lisp implementation version: GCL 2.6.8

    5.26.0gcl gives effectively -%i*%pi/2

    (%i1) integrate(sin(x)^2/x,x,minf,inf);
    Principal Value
    (%o1) -log(-1)/2
    (%i2) float(%);
    (%o2) -1.570796326794897*%i
    (%i3) build_info()$
    Maxima version: 5.26.0
    Maxima build date: 22:48 1/15/2012
    Host type: i686-pc-mingw32
    Lisp implementation type: GNU Common Lisp (GCL)
    Lisp implementation version: GCL 2.6.8

     
  • Dan Gildea

    Dan Gildea - 2012-01-28

    Fixed in defint.lisp.
    principal-value-integral: leave $logabs as is

     
  • Dan Gildea

    Dan Gildea - 2012-01-28
    • assigned_to: nobody --> dgildea
    • status: open --> closed
     

Log in to post a comment.