Finding branches where general solution is possible

*To*: mathgroup at smc.vnet.net*Subject*: [mg131843] Finding branches where general solution is possible*From*: Narasimham <mathma18 at gmail.com>*Date*: Wed, 16 Oct 2013 05:00:36 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-outx@smc.vnet.net*Delivered-to*: mathgroup-newsendx@smc.vnet.net

For following function with period 2 Pi in which branches is it possible to get a general solution? Regards Narasimham DSolve[{si''[th] Tan[si[th]]==(1+si'[th]) (1+2si'[th]),si[0]==Pi/4 },si,th] NDSolve[{si''[th] Tan[si[th]]==(1+si'[th]) (1+2si'[th]),si'[0]==0,si[0]==Pi/4},si,{th,0,6Pi}]; SI[u_]=si[u]/.First[%];Plot[SI[th],{th,0,6Pi}] DSolve::bvnul: For some branches of the general solution, the given boundary conditions lead to an empty solution.>>