Re: NDSolve problem with switching equations

*To*: mathgroup at smc.vnet.net*Subject*: [mg106226] Re: NDSolve problem with switching equations*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Tue, 5 Jan 2010 01:48:28 -0500 (EST)

On 1/4/10 at 5:59 AM, btreat1 at austin.rr.com (DrMajorBob) wrote: >First, we need a square wave of amplitude one, zero up to 0.5, 0 >from .05 to 1.0, with period 1. >The following will do well enough: >Plot[UnitStep@Sin[2 Pi t], {t, 0, 2}] =46WIW, if you are using vers 7 or later there is the built in function SquareWave. That is Plot[.5 + .5 SquareWave[t],{t, 0, 2}] produces the same graphic as your code. And using .5 + .5 SquareWave[t] in place of UnitStep@Sin[2 Pi t] in the arguments to NDSolve appears to get the identical solution. At least the error plots look the same. On my machine, subjectively, there didn't seem to be any performance difference for either function for producing a square wave.