Re: Reasonable integration speed? (24 hrs and counting)
- To: mathgroup at smc.vnet.net
- Subject: [mg68063] Re: Reasonable integration speed? (24 hrs and counting)
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Fri, 21 Jul 2006 17:35:59 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <e9nkvm$9vo$1@smc.vnet.net> <e9q97p$7tf$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
axlq wrote:
> Update: Going on 48 hours now. I'm concerned that something is
> hung, but I fear aborting the job if there's any chance it may
> actually be progressing to a solution. I'm unfamiliar with what I
> can expect in terms of Mathematica's speed of solving an integral.
> Is this reasonable? Is there a setting somewhere that shows some
> sort of progress indicator?
>
> -Alex
>
> In article <e9nkvm$9vo$1 at smc.vnet.net>, axlq <axlq at spamcop.net> wrote:
>> I downloaded the trial version of Mathematica to see if it could
>> solve a complex integral. After getting comfortable with solving
>> simple integrals, I input my target problem:
>>
>> In[1]:= f[x] = Sqrt[a^2+(q-x)^2]
>>
>> In[2]:= Integrate[Cos[(2*n + 1)*Pi*x/d]*
>> (Exp[-I*k*f[x]]/(4*Pi*f[x]^5)*((1 + I*k*f[x])*(2*f[x]^2 - 3*a^2)
>> + (k*a*f[x])^2) * I*d/(2*Pi* w) + p), {x, -d/2, d/2}]
>>
>> Observations:
>>
>> 1. It's been sitting there for over 24 hours now.
>>
>> 2. Task Manager shows Mathematica's CPU usage at a constant 50%.
>>
>> 3. The "Kernel" pull-down menu has "Interrupt Evaluation" grayed out.
>> I can abort it.
>>
>> 4. Mathematica won't solve any subsequent problem in another window
>> (seems like the first one is occupying a queue).
>>
>> Earlier I tested some simple function-reference integrals (e.g.
>> defining f[x] first and then integrating f[x]dx) and they worked.
>>
>> What sort of speed can I expect from this? Is 24 hours too long to
>> solve a problem like this on a 2.6 GHz Windows XP platform with 1.25
>> GB RAM? Is Mathematica hung up on something? Is the fact that I'm
>> using the trial version make any difference? Did I do something
>> wrong?
>>
>> Thanks.
>> -Alex
>
Hi Alex,
I think you can abort the evaluation. Here is what I get on my system:
f[x] = Sqrt[a^2 + (q - x)^2]
Integrate[Cos[(2*n + 1)*Pi*(x/d)]*((Exp[(-I)*k*f[x]]/(4*Pi*f[x]^5))*((1
+ I*k*f[x])*(2*f[x]^2 - 3*a^2) + (k*a*f[x])^2)*I*(d/(2*Pi*w)) + p), {x,
-d/2, d/2}]
displays after several minutes
Integrate::"gener" : "Unable to check convergence.
(I aborted the still running evaluation loop after that.)
$Version
"5.2 for Microsoft Windows (June 20, 2005)"
Regards,
Jean-Marc