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It's not hung; it's just slow. With the adaptive plotter, maxima is trying very hard to refine the graph because every calculated point is not a number which makes maxima think some kind of discontinuity exists. I think this is a deficiency caused by gcl not quite supporting the needed feature to make it stop early.
Perhaps the level to which the adaptive plotter divides intervals should be...
2009-11-09 23:17:50 UTC by rtoy
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First, I think it is not a problem of the integration of signum. Maxima does not find the integral and returns a noun form (without abs_integrate). That is O.K., because we have the abs_integrate package.
Here another example:
(%i28) integrate(sin(x)*expintegral_ei(x),x,-2,y);
(%o28) 'integrate(expintegral_ei(x)*sin(x),x,-2,y)
(%i29) plot2d(%,[y,-1,2]);
At this point Maxima hangs on...
2009-11-09 21:32:35 UTC by crategus
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Sorry, I have no mathematical proof. I have come to the conclusion because of
the follwing:
1. The function floor(x) is discontinuous.
2. The function x*floor(1/x) has an infinite number of points of discontinuity
in any infinitesimal intervall when aproching zero.
3. Therefore, the function does not approach a limit.
I could be wrong.
Dieter Kaiser.
2009-11-09 21:11:11 UTC by crategus
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riotorto committed patchset 7827 of module maxima to the Maxima -- GPL CAS based on DOE-MACSYMA CVS repository, changing 1 files.
2009-11-09 19:06:39 UTC by riotorto
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riotorto committed patchset 7826 of module maxima to the Maxima -- GPL CAS based on DOE-MACSYMA CVS repository, changing 2 files.
2009-11-09 19:00:02 UTC by riotorto
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riotorto committed patchset 7825 of module maxima to the Maxima -- GPL CAS based on DOE-MACSYMA CVS repository, changing 1 files.
2009-11-09 18:02:11 UTC by riotorto
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Isn't the limit 1? Let any x small enough, 1/x = n + e, where n is an integer and e < 1. Then floor(1/x) = n and x*floor(1/x) is n/(n+e) = 1 - e/(n+e). As n gets larger (and x gets smaller), this approaches 1.
Did I make a mistake?.
2009-11-09 17:17:50 UTC by rtoy
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As mentioned in the last posting this bug report seems to be invalid.
Closing this bug report as invalid.
Dieter Kaiser.
2009-11-09 17:09:19 UTC by crategus
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With Maxima 5.19post I get a noun form too. There have been serveal changes the last time to improve limit. Furthermore, I think the limit of the example is not defined. Therefore, it seems to be not wrong to return a noun form.
Setting the status to pending and works for me.
Dieter Kaiser.
2009-11-09 16:59:43 UTC by crategus
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More desired features from Bug report ID: 2893431
Hi All,
1) Inverse Laplace transforms should have unit_step(t) multiplied on them,
and they don't.
2) It appears that Maxima doesn't recognize the delay operator exp(-sT)
for a delay of T seconds.
It seems these should be pretty easy to fix.
Best regards,
Rob.
2009-11-09 16:32:17 UTC by crategus
