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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

> 





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Daniel Huber

Metrohm Ltd.

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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>




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