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Re: NDSolve Percision

  • To: mathgroup at smc.vnet.net
  • Subject: [mg85522] Re: NDSolve Percision
  • From: dh <dh at metrohm.ch>
  • Date: Wed, 13 Feb 2008 04:17:22 -0500 (EST)
  • References: <fopbtt$c4m$1@smc.vnet.net>


Hi Alex,

look up the option "AccuracyGoal" of NDSolve.

hope this helps, Daniel



Alex Cloninger wrote:

> So I'm running a program that is trying to use NDSolve and parametrically plot the results.  The result is periodic, so it should cycle back on itself with a period of 2Pi.  It does that, but if I run from {t,0,20Pi} is starts to miss the initial point by more and more.  Basically, it's spiraling outward at a slow but unwanted rate.  This will be a problem for when I increase the difficulty of the function.

> 

> How do I increase the precision of NDSolve to make it keep more decimals and make the answer more accurate?

> 

> The function is

>  

> solution = NDSolve[{x'[t] == 2p[t], x[0] == 2, 

> p'[t] == -2x[t],p[0] == N[Sqrt[-3], 50]}, {x, p}, {t,0,20Pi}]

> 

> If you could help me out, I'd really appreciate it.  Thanks.

> 




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