How can I solve multivariate differential equations?

I need to solve an ODE depending on 4 variables (t,x,y,z), with partial derivatives of order 2:

(dt + dz)^2 (f)- laplacian(f)=0

How can I write it on matlab? For instance "D([x y ...],f)" returns undefined function "D"...

[John D'Errico]

Well, yes, just making up your own notation/syntax in MATLAB will likely fail to produce working code. This is not an ODE by the way, but a PDE.

There are PDE tools in MATLAB. So you might start reading the help for those tools. Read through some examples. But I'd guess that really you need to start learning MATLAB, at least basic syntax, instead of jumping into the deep end of the pool.

You might also think about reading about numerical methods to solve PDEs. Understanding how to solve a problem can be valuable even when you try to use tools that do the work for you.

[David GASPERINI]

I saw this D in this page:

http://nl.mathworks.com/help/symbolic/mupad_ref/d.html?refresh=true#stdlib-d-rewrite

Is it also my own notation? I do not think that I don't understand the problem, only I would like to implement this equation, is there a notation to do this? I mean to write partial derivatives of any order of a non explicitly defined function (by the way the expected solution of our equation)?

[Torsten]

Please write out your equation in the usual mathematical notation.

From what you wrote above, I don't even know which equation you are trying to solve.

Best wishes

Torsten.

[Vaibhav Awale]

The D that is mentioned in this page should be used in MuPAD and not in MATLAB command window or MATLAB script. As John pointed out, to solve this PDE, PDE toolbox can be helpful, but it is important to understand basic syntax and numerical methods to solve PDEs