Re: question about ndsolve

*To*: mathgroup at smc.vnet.net*Subject*: [mg131661] Re: question about ndsolve*From*: rchagw at gmail.com*Date*: Tue, 17 Sep 2013 21:34:53 -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*References*: <l0mhfr$ldc$1@smc.vnet.net>

On Tuesday, September 10, 2013 3:24:43 AM UTC-4, Hagwood, Charles R wrote: > I know the following differential equation has a solution, but cannot get NDSolve to find it. > > > > > > dgamma[s_,a_]:=1+9.6*(s-1)^2*s+9.6*s^2*(s-1) > > q2[x_]:=Sqrt[2*Pi]*{-Sin[2*Pi*x],Cos[2*Pi*x]} > > q1[x_,a_]:=Sqrt[2*Pi*dgamma[x,a]]*{-Sin[2*Pi*gamma[x,a]],Cos[2*Pi*gamma[x,a]]} > > > > > > h1[x_]:=q2[x].q2'[x] > > h2[x_]:=q2[x].q2[x] > > > > > > sol=NDSolve[{-6*y'[x]^2*(q1[x,.3].q2'[y[x]]) +6*y'[x]^(5/2)*h1[y[x]]+y''[x]*(q1[x,.3].q2[y[x]])-y''[x]*y'[x]^(1/2)*h2[y[x]]==0,y[0]==0,y[1]==1},y,{x,0.01,1},Method->{"Shooting","StartingInitialConditions"->{y[0]==0}}] > > > > I get the error NDSolve::ntcs: Cannot solve constraint equations for initial conditions. <http://reference.wolfram.com/mathematica/ref/message/NDSolve/ntcs.html> > > > > > > The solution is > > > > y[x_]:=x+16*a*x^2*(x-1)^2 > > a=.3; > > > > The following expression is zero for all values of x > > > > -6*y'[x]^2*(q1[x,.3].q2'[y[x]]) +6*y'[x]^(5/2)*h1[y[x]]+y''[x]*(q1[x,.3].q2[y[x]])-y''[x]*y'[x]^(1/2)*h2[y[x]]/.x->.9 > > > > > > Does anyone know what is going wrong with NDSolve? > > > > Charles Hagwood gamma[s_,a_]:=s+16*a*s^2*(s-1)^2