Having a system of three state I put the odes in a function and the script to solve the given function I'm getting NaN for output of ode45

my function is

function xdot=func4(t,x)

A=[0 1 0;0 0 1;-1 -2 -3]
B=[0 0;0 1;1 0]
C1=[0 1]'
C2=[1 0 ;0 1]
C3=[1 0]'

s=C1*x(1)+C2*[x(2);x(3)]+C3*x(1)^(3/4)
u=[x(1);0]+[x(2)+x(3);-x(3)]-[0;3/5*x(2)*x(1)^-2/5]-[0 0.1;0.1 0]*s/norm(s)+[x(1);0]+[2*x(2)+2.9*x(3);-0.1*x(2)-x(3)]

xdot=A*x+B*u
 end

and by using ode 45 it give me nan state plese help me

tspan=[0 8]
x0=[0;-0.15;0.1]

[t,x]=ode45('func4',tspan,x0)

[madhan ravi]

upload the latex form of the equation

Answer 1

[Walter Roberson]

In your sub-expression

[0;3/5*x(2)*x(1)^-2/5]

you have the problem that x(1) can go to 0, leading to a division by 0.

x0=[0;-0.15;0.1]

... and x(1) being 0 is your initial condition so it is guaranteed to be a problem.

[Sunil Ojwani]

thank you a lot