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MathGroup Archive 2006

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Re: Loop and Lost values - The Sequel

  • To: mathgroup at smc.vnet.net
  • Subject: [mg65542] Re: Loop and Lost values - The Sequel
  • From: "Valeri Astanoff" <astanoff at yahoo.fr>
  • Date: Thu, 6 Apr 2006 06:53:21 -0400 (EDT)
  • References: <e108u4$lia$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

To my mind the trouble is that, implicitly,
you test floating point values for equality,
which is usually not recommended.

Assuming the equation depends on t1,
you could, for example, proceed this way :


t1[i_Integer] = 94.8+0.001*i;

Do[eq = {x'[t]==0.001*x[t]*t1[i], x[0]==1};
   sol = NDSolve[eq,{x},{t,0,10}];
   xt[i] = Interpolation[Table[{t,x[t]/.sol//First},{t,0,10}]],
{i,0,199}];

Do[Print[{t1[i], xt[i][3.2]}], {i,0,9}]


{94.8,1.3544}
{94.801,1.3544}
{94.802,1.35441}
{94.803,1.35441}
{94.804,1.35442}
{94.805,1.35442}
{94.806,1.35443}
{94.807,1.35443} 
{94.808,1.35444} 
{94.809,1.35444}


hth

V.Astanoff


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