Solving Nonlinear system of differential equations using Matlab

How can i solve this system,

u''=(w'^2)'

w''''=(u'w'+w'^3)'

I have a problem writing the following expressions (w'^2)' and (w'^3)' in the standard form of Matlab ode solvers

Thanks

[ash]

Any help? :)

[Torsten]

Any questions about my answer ?

Best wishes

Torsten.

[Walter Roberson]

Torsten, somehow your answer got marked as potential spam. I do not know if it would have been visible to non-moderators.

Answer 1

[Torsten]

u''=2w'*w''
w''''=u''*w'+u'*w''+3w'^2*w''=5w'^2'w''+u'*w''

->

u1'=u2
w1'=w2
w2'=w3
w3'=w4
u2'=2*w2*w3
w4'=5*w2'^2*w3+u2*w3

Here,

u1=u, u2=u', w1=w, w2=w', w3=w'', w4=w'''.

Best wishes

Torsten.

[ash]

oh ... Thanks a lot, I don't know how I missed that :)

Regards Ashraf

[Torsten]

Should read

w4'=5*w2^2*w3+u2*w3

instead of

w4'=5*w2'^2*w3+u2*w3

Best wishes

Torsten.