Re: Dsolve ODE

*To*: mathgroup at smc.vnet.net*Subject*: [mg89137] Re: Dsolve ODE*From*: dh <dh at metrohm.ch>*Date*: Mon, 26 May 2008 06:25:07 -0400 (EDT)*References*: <g18hoc$kft$1@smc.vnet.net> <g1avme$fbo$1@smc.vnet.net>

Hi, the initial conditions can not be the reason for failure as the following example shows: DSolve[{y''[x]+4y[x]==0,y[0]==1,y[Pi/4]==4},y,x]Daniel Steven Siew wrote: > On May 24, 5:57 pm, sokol <mirek.h... at gmail.com> wrote: >> Hello, I've tried to solve 2nd order ODE with Dsolve but failed. >> >> In[1]: >> DSolve[{y''[x] + Cot[x]*y'[x] + Sin[x]*y[x] == 0, >> y[\[Pi]/2] == \[Alpha], y[(7*\[Pi])/8] == \[Beta]}, y[x], x] >> >> out[1]: >> DSolve[{y''[x] + Cot[x]*y'[x] + Sin[x]*y[x] == 0, >> y[\[Pi]/2] == \[Alpha], y[(7*\[Pi])/8] == \[Beta]}, y[x], x] >> >> Any hint? Thanks. > > I believe that your initial conditions are insufficient. > > I think you need > > y'[x1]==something > y[x2]==something else > > for your initial conditions > -- Daniel Huber Metrohm Ltd. Oberdorfstr. 68 CH-9100 Herisau Tel. +41 71 353 8585, Fax +41 71 353 8907 E-Mail:<mailto:dh at metrohm.com> Internet:<http://www.metrohm.com>