Spring Mass Problem - Code not working

I am trying to learn to model with matlab. I started at the symbolic math toolbox and went through the Mass-Spring-Damper System Modeling. The link is given here

http://www.mathworks.com/products/symbolic/code-examples.html?file=/products/demos/symbolictlbx/Mass_Spring_Damper/MSD_published.html

However, the code given there starts to give error. What am I doing wrong?

My input was (as copied from the link)

f1 := ode({m*x''(t) + R*x'(t) + k*x(t), x(0) = 0 , x'(0) = 1}, x(t))

The error I received was

f1:= ode({m*x''(t) + R*x'(t) + k*x(t), x(0) = 0 , x'(0) = 1}, x(t))
   |
Error: The expression to the left of the equals sign is not a valid
target for an assignment.

Can someone tell me what i am doing wrong?

Answer 1

[Sean de Wolski]

The code above is part of the MuPad language and needs to be run inside of a MuPad notebook, not at the MATLAB command prompt.

You can open a MuPad notebook by clicking the MuPad app or running the following at the command line:

>>mupad

Answer 2

[Image Analyst]

Well I don't know how to use the Symbolic toolbox, so I could be wrong, but I'd try getting rid of the colon and use only the equal sign. What language are you most familiar with, Pascal? Or maybe some other language that uses := ????? I've never seen that in MATLAB, but then again, I don't use the Symbolic Math toolbox and I don't know if it has special syntax.

[Sean de Wolski]

It does, it breaks all of the rules :)