Re: Modulus Question
- To: mathgroup at smc.vnet.net
- Subject: [mg16561] Re: Modulus Question
- From: Paul Abbott <paul at physics.uwa.edu.au>
- Date: Tue, 16 Mar 1999 04:00:28 -0500
- Organization: University of Western Australia
- References: <7c5c7i$7so@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Guy Gilliland wrote:
> I am trying to take the modulus of a function and am having difficulty.
> The following is my code:
>
> soln=NDSolve[{x'[t]==y[t],x[0]==0.4,
> y'[t]==-gamma1 * y[t] - Sin[x[t]] + A1 * Cos[z[t]],
> y[0]==1.2,z'[t]==w,
> z[0]==0},{x,y,z},{t,0,1500},MaxSteps\[Rule]50000]
>
> Before I do a parametric plot, I want to do the following:
>
> x[t] = x[t] Mod 2*pi (* limit x to belong to interval from 0 to 2*pi
>
> I don't know how to do this. Using the Mod function gives recursion
> errors (i.e., Mod[x[t],2*pi] doesnt' work).
Just apply Mod to x[t], e.g.,
Plot[Evaluate[Mod[x[t] /. soln, 2Pi]], {t, 0, 1500}];
or, in 3D,
ParametricPlot3D[Evaluate[{Mod[x[t], 2Pi], y[t], z[t]} /. soln],
{t, 0, 1500}, BoxRatios -> {1, 1, 1}]
Cheers,
Paul
____________________________________________________________________
Paul Abbott Phone: +61-8-9380-2734
Department of Physics Fax: +61-8-9380-1014
The University of Western Australia
Nedlands WA 6907 mailto:paul at physics.uwa.edu.au
AUSTRALIA http://www.physics.uwa.edu.au/~paul
God IS a weakly left-handed dice player
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