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Re: question

  • To: mathgroup at
  • Subject: [mg43534] Re: [mg43473] question
  • From: Hugh Walker <hwalker at>
  • Date: Fri, 19 Sep 2003 03:41:57 -0400 (EDT)
  • Sender: owner-wri-mathgroup at

On Thursday, September 18, 2003, at 04:38 AM, Aslaninejad Morteza wrote:

> I have solved a differential equation numerically with NDSolve and 
> now, I
> would like to do the following step but I don't know how?
> 1- Take the derivative of the answer first.
> 2- Sum the square of answer and the square of the derivative secondly.
> thanks in advance

Hi Aslaninejad;

sol = x/.NDSolve[{x''[t]+0.3 x'[t]+x[t]==0, x[0]==1,x'[0]==0},
img1 = Plot[sol[t],{t,0,10}];
img2 = Plot[D[sol[t],t]//Evaluate,{t,0,10}];
img3 = Plot[D[sol[t],{t,2}]//Evaluate,{t,0,10}];

Best wishes,

Hugh Walker
Gnarly Oaks

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