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MathGroup Archive 2004

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RE : Interpolating function

  • To: mathgroup at smc.vnet.net
  • Subject: [mg49187] RE : [mg49158] Interpolating function
  • From: "Florian Jaccard" <florian.jaccard at eiaj.ch>
  • Date: Tue, 6 Jul 2004 03:34:51 -0400 (EDT)
  • Sender: owner-wri-mathgroup at wolfram.com

It is ! Just use y2'[t] and y2''[t] !

ODE = 0 == Derivative[2][y][t] + (1 - y[t])/Derivative[1][y][t];
NDSolve[{ODE, y[1] == 1, Derivative[1][y][1] == 1}, y, {t, -2, 3}];
y2[u_] = y[u] /. First[%];
Plot[{y2[t], Derivative[1][y2][t], Derivative[2][y2][t]}, {t, -2, 3}, Epilog
-> {Text["y", {3.3, y2[3]}], Text["y'", {3.3, Derivative[1][y2][3]}],
     Text["y''", {3.3, Derivative[2][y2][3]}]}, PlotRange -> {{-2, 3.5},
{-5, 5}}];
 
(Convert to StandardForm)
 
What is your y3[t] ?
 
 
F.Jaccard
 
 
-----Message d'origine-----
De : "G.L.Narasimham" [mailto:mathma18 at hotmail.com]
Envoyé : lundi, 5. juillet 2004 10:55
À : mathgroup at smc.vnet.net
Objet : [mg49158] Interpolating function
 
ODE=0==y''[t]+(1-y[t])/y'[t];
NDSolve[{ODE,y[1]==1,y'[1]==1},y,{t,-2,3}];
y2[u_] =  y[u] /. First[%];
yd = Dt[y2[t],{t,1}]; ydd = Dt[y2[t],{t,2}];
Plot[ {y2[t],y3[t],yd,ydd},{t, -2, 3 }];
" Is it not possible to directly access
 y'[t]and y''[t] plots without Dt? "
 
 


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