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Modulus Question

• To: mathgroup at smc.vnet.net
• Subject: [mg16396] Modulus Question
• From: Guy Gilliland <guy20 at wharton.upenn.edu>
• Date: Thu, 11 Mar 1999 02:16:58 -0500
• Organization: Wharton
• Sender: owner-wri-mathgroup at wolfram.com

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).

Thanks in advance for your assistance.  Please email me at
guy20 at wharton.upenn.edu

Guy Gilliland

• Follow-Ups:
  • Re: Modulus Question
    • From: Jurgen Tischer <jtischer@col2.telecom.com.co>