third order differential equation

Hi I,m new to matlab and I want solve this differential equation x(3)+ k/c x(2)+ k/m x(1)=0

m=50 c=50 k=1000

Any help would be great. Thanks in advance, leili

Answer 1

[Azzi Abdelmalek]

Save this function as myfcn.m

function dx=myfcn(t,x)
dx=zeros(3,1)
m=50;
c=50 ;
k=1000;
dx(1)=x(2);
dx(2)=x(3);
dx(3)=(-k/c)*x(3)-(k/m)*x(2);

Call the function myfcn

tspan=[0 10];
x0=[0.1;0.2;0.3]  % Initial conditions
[t,x]=ode45(@myfcn,tspan,x0)
plot(t,x)

Answer 2

[Venkata Sai Ram Aripirala]

How to write f''' + f'f'' = o in matlab

[madhan ravi]

ask a separate question @Venkata

[Venkata Sai Ram Aripirala]

eqn ( f''' + f*f''== 0 ) Is this the foemat to put in Matlab

[madhan ravi]

no, I mean post a separate question because this is not related to the original question