NDSolve problem with switching equations

*To*: mathgroup at smc.vnet.net*Subject*: [mg106163] NDSolve problem with switching equations*From*: Haibo Min <haibo.min at gmail.com>*Date*: Sun, 3 Jan 2010 03:42:43 -0500 (EST)

Hello, everyone. I am trying to solve a switching ND problem using NDSolve. Specifically, suppose the system equation is y1'[t]==y2; y2'[t]==1000(1-y1^2)y2-y1; y1(0)==0;y2(0)==1; Then every half a second (0.5s), the system equation transforms to y1'[t]==y2; y2'[t]==1000(1+y1^2)y2; and then, after 0.5s, it transforms back again. How to address this problem? Thank you! haibo

**Follow-Ups**:**Re: Re: NDSolve problem with switching***From:*DrMajorBob <btreat1@austin.rr.com>

**Re: NDSolve problem with switching equations***From:*Haibo Min <haibo.min@gmail.com>

**Re: NDSolve problem with switching equations***From:*DrMajorBob <btreat1@austin.rr.com>