integrate(1/(sin(x)^2+1),x,a,b)?



Here is what I get using Maple 10

>  integrate(1/(sin(x)^2+1),x=0..z);
>
Warning, unable to determine if Pi*_Z3+1/2*Pi is between 0 and z; try
to use assumptions or set _EnvAllSolutions to true


                            z
                           /
                          |        1
                          |   ----------- dx
                          |         2
                         /    sin(x)  + 1
                           0

>  integrate(1/(sin(x)^2+1),x);
>

                          1/2                1/2
                     1/2 2    arctan(tan(x) 2   )

> _EnvAllSolutions := true:
> integrate(1/(sin(x)^2+1),x=0..z);
>

  {
  {      1/2 /               1/2         -Pi + 2 z    \          Pi
  { 1/2 2    |arctan(tan(z) 2   ) + ceil(---------) Pi| , z < - ----
  {          \                             2 Pi       /          2

              1/2
          Pi 2             Pi
        - ------- , z = - ----
             4             2

                           1/2   1/2        Pi
        1/2 arctan(tan(z) 2   ) 2    , z < ----
                                            2

            1/2
        Pi 2           Pi
        ------- , z = ----
           4           2

             1/2 /               1/2             -Pi + 2 z      \
        1/2 2    |arctan(tan(z) 2   ) + Pi floor(---------) + Pi| ,
                 \                                 2 Pi         /

         Pi
        ---- < z
         2


Barton

-----maxima-bounces at math.utexas.edu wrote: -----

>To: Maxima List <maxima at math.utexas.edu>
>From: Raymond Toy <raymond.toy at ericsson.com>
>Sent by: maxima-bounces at math.utexas.edu
>Date: 06/27/2007 10:51AM
>Subject: integrate(1/(sin(x)^2+1),x,a,b)?
>
>Bug 1741705
>>=4933&atid=104933>
>
>says the integral from 0 to 8 is wrong.  I have a fix for this that
>depends on floor(x/%pi) working correctly when x is a number, or
>expression possibly including %pi.  I believe floor is working
>correctly, and the changes I've made are also working correctly.
>
>However, what should maxima do for the integral from 0 to z, say?
>Currently, it returns
>
>sqrt(2)/2*atan(sqrt(2)*sin(z)/cos(z)) + %pi/sqrt(2)
>
>This isn't quite right, unless you carefully select the correct branch
>for atan.  This is, howveer, the correct answer if z < 2*%pi.
>
>What should maxima do here?  What do Macsyma, Maple, and/or
>Mathematica return for this integral?
>
>Ray
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