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Re: Incredible slow Plot

  • To: mathgroup at smc.vnet.net
  • Subject: [mg120200] Re: Incredible slow Plot
  • From: DrMajorBob <btreat1 at austin.rr.com>
  • Date: Tue, 12 Jul 2011 07:01:13 -0400 (EDT)
  • References: <iv9etb$dg1$1@smc.vnet.net> <201107111058.GAA08408@smc.vnet.net>
  • Reply-to: drmajorbob at yahoo.com

> and that was it. However I don't understand this. Was the problem the
> "size" and "amount" of interpolated functions?

I don't understand it either. The two methods seem equivalent, but this  
code

> sol=NDSolve[{eqns, cond},f,{t,0,1200}][[1]];
> a=sol[[1, Something, 2]]
> b=sol[[1, Something+1, 2]]

suggests that you're solving for one function f in the first line, and  
YET, you're extracting two solutions a and b in the next two lines. That's  
not possible, so you're not showing us the code you actually used. (We  
know that anyway, since "eqns", "cond", and "Something" are undefined.)

I suspect in the real code, the two methods that seem equivalent are NOT  
equivalent at all.

Bobby

On Mon, 11 Jul 2011 05:58:03 -0500, Iván Lazaro <gaminster at gmail.com>  
wrote:

> Hi!
>
> Yes, I tried
>
>  sol=NDSolve[{eqns, cond},f,{t,0,1200}][[1]];
>  Plot[Evaluate[f[t]/.sol],{t,0,1200}],
>
> but that was a pain. Thanks to Bobby I managed to solve my speed problem:
>
> Instead of
>
> sol=NDSolve[{eqns, cond},f,{t,0,1200}][[1]];
> Plot[Evaluate[f[t]/.sol],{t,0,1200}],
>
> I selected the specific solutions I needed, and Set them to a variable
> that then I plot:
>
>
>
> sol=NDSolve[{eqns, cond},f,{t,0,1200}][[1]];
> a=sol[[1, Something, 2]]
> b=sol[[1, Something+1, 2]]
>
> Plot[{a[t],b[t]}],{t,0,1200}],
>
> and that was it. However I don't understand this. Was the problem the
> "size" and "amount" of interpolated functions?
>


-- 
DrMajorBob at yahoo.com


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