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How to get the ceofficients of a expression derived by ODE or integral ? For exampli,C1 and C2 in u

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Guoyao.Li
Guoyao.Li on 25 Aug 2021
Edited: Guoyao.Li on 26 Aug 2021
syms rho a b E omega u(r) mu
sigma_r=E/(1-mu^2)*(diff(u,r)+mu*u/r);
sigma_theta=E/(1-mu^2)*(mu*diff(u,r)+u/r);
u=dsolve(diff(r*sigma_r,r,1)-sigma_theta+rho*omega^2*r^2==0)
u = 

Answers (1)

James Tursa
James Tursa on 25 Aug 2021
Typically these would be obtained by combining the solution with initial values for u. Do you have initial values?
  1 Comment
Guoyao.Li
Guoyao.Li on 26 Aug 2021
Thanks!!!
I know that the specific solution for u needs initial conditions,but I want to extract the ceofficients of general solution,which are C1 and C2.And then using ''subs'' in MATLAB to subsitute C1 and C2 with specific value.However,it fails if I directly use syntax "u=subs(u,[C1 C2],[1 2])".
I have tried to use "children" syntax in MATLAB to extract C1 and C2 in u and it succeeds, but I think it's a little tedious.Is there any simple way to do it?

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