4th order DE



*Thanks to Richard Fateman for the answer.

I don't have access to Maple anymore, but this did the job:

  diffeqw:=   ({diff((1-alpha*xi)*diff(w(xi),xi$2),xi$2) = 1, \
               w(0)=0, \
               D(w)(0)=0, \
               w(1)=0, \
               D(D(w))(1)=0}, \
               w(xi));

  wsol:=dsolve(diffeqw);
  wsol:=op(2,wsol);

and MuPAD has something like it:

  diffeqw:=ode({diff((1-1/2*xi)*diff(w(xi),xi$2),xi$2) = 1, \
               w(0)=0, \
               D(w)(0)=0, \
               w(1)=0, \
               D(D(w))(1)=0}, \
               w(xi));
  w0:=solve(diffeqw);
  w0:=op(w0,1);

Both these ways seem easier than converting the problem to
a system of 4 first order ODEs.

Best regards,

Esben Byskov

*

Esben Byskov, Ph.D., Dr.Techn.
Professor Emeritus of Structural Analysis
Department of Civil Engineering
Aalborg University
Sohngaardsholmsvej 57
DK-9000 Aalborg
Denmark

Phone:   +45 3963 7328
e-mail:  eb at civil.aau.dk



On 2011-01-07 00:16, Richard Fateman wrote:
> On 1/6/2011 3:02 PM, Esben Byskov wrote:
>> *Hi,
>>
>> Can anyone tell me if there are ways to solve 4th order ordinary
>> differential equations in maxima.  I am particularly interested
>> in boundary value problems rather than initial value problems.*
> *I don't know if someone has written this out, but the usual approach that
> you might use by hand can also be done by Maxima.
>
> I expect that is to write this out as a system of 4 first order ODEs, and
> solve this system.  I don't know if there is a single command
> in some package to do this,
> but all the needed components are around.**
>
> *