Re: How to rectify the error for NDSolve ?

• To: mathgroup at smc.vnet.net
• Subject: [mg127173] Re: How to rectify the error for NDSolve ?
• From: Rahul Chakraborty <rahul.6sept at gmail.com>
• Date: Thu, 5 Jul 2012 06:11:55 -0400 (EDT)
• Delivered-to: l-mathgroup@mail-archive0.wolfram.com

```I have made the changes as suggested by Bob but still some errors are there:

Clear[x,Q,\[CapitalGamma],\[Phi]];
Q=100;
\[CapitalGamma]=50;
Subscript[\[Omega], 0]=10;
Subscript[V, p]=1/2;
Subscript[C, 0]=406 * 10^-6;
\[Phi]=90;
Subscript[V, 1][t]=Sqrt[2] Subscript[V, p]Sin[2Subscript[\[Omega], 0]t];
eqn= x''[t]+Subscript[\[Omega], 0]/Q x'[t]+(Subscript[\[Omega], 0]^2)[1+Subscript[c, 0]Subscript[V, 1][t]]x[t]==\[CapitalGamma] Sin[Subscript[\[Omega], 0]t+\[Phi]]//Simplify;
sol=NDSolve[{eqn,x[0]==1/2,x'[0]==0},x[t],{t,0,25}][[1]]
ParametricPlot[Evaluate[{x[t]/.sol,D[x[t]/.sol,t]}],{t,0,25},Frame->True,AxesLabel->{"t",Overscript[\[Theta],"."]},AspectRatio->1]

Errors:

Set::write: Tag Times in (0.707107 Sin[20 t])[t] is Protected. >>

NDSolve::ndnum: Encountered non-numerical value for a derivative at t == 0.`. >>

Plz suggest what shall i do to get the solution.

Regards,
rc

```

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