#1140 integrate loops

closed
nobody
5
2007-07-06
2007-03-01
Anonymous
No

Hello

I had to interrupt maxima when it was at calculating the following integral:

(%i101) m(r,th);

2 2
(%o101) SQRT(z + 2 r rM (1 - COS(th)) + (rM - r) )
(%i102) F(d);

2
2 d0
4 A d0 (epsi - --- + 1) w
2
d
(%o102) - --------------------------
3
d
(%i103) integrate(1/m(th,r)^2*F(m(th,r))*z^2,th,0,%PI);

2 2 2 2
Is z - COS (r) rM + rM positive, negative, or zero?

pos;
2 2 2
Is z + (1 - COS (r)) rM positive, negative, or zero?

pos;
Maxima encountered a Lisp error:

Console interrupt.

Best wishes,
Jocelyn

Discussion

  • Nobody/Anonymous

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    Version is Maxima 5.9.1

     
  • Nobody/Anonymous

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    sorry about the mess...
    the functions are:
    m(r,th):=sqrt(z^2+(rM-r)^2+2*rM*r*(1-cos(th)));

    and
    F(d):=-4*w/d*(d0/d)^2*(1+epsi-(d0/d)^2)*A;

     
  • Raymond Toy

    Raymond Toy - 2007-03-03

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    It does seem to loop. Not sure if it really does, because I didn't wait for very long.

    Note, however, that all of the integrals are of the form 1/(th^2+a*th*b)^(n/2) where n is odd (5 or 7 here). Maxima can evaluate all of these integrals quite quickly. I think, but I'm not sure, that maxima is busy simplifying complicated intermediate expressions because the coefficients are not simple.

     
  • Raymond Toy

    Raymond Toy - 2007-03-07

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    What is the integrand? You have the function m(r,th), but the integral says m(th,r). Given the limits of 0 and %pi, I think your integrand is wrong. Did you really want m(r,th)?

     
  • Raymond Toy

    Raymond Toy - 2007-06-21

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    No additional information from poster.

    Marking as Pending

     
  • Raymond Toy

    Raymond Toy - 2007-06-21
    • status: open --> pending
     
  • SourceForge Robot

    • status: pending --> closed
     
  • SourceForge Robot

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    This Tracker item was closed automatically by the system. It was
    previously set to a Pending status, and the original submitter
    did not respond within 14 days (the time period specified by
    the administrator of this Tracker).

     

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