Discrete Math Differential equation

How do I program in Matlab the following:

dy/d(x/constant) = f( x/constant, y)

[madhan ravi]

Shall we say f is a function of x and y? Why is it x/constant ?

[Hassan Ghanem]

That's how the problem statement wants the independent variable to be expressed.

[Torsten]

Use an ODE integrator (ODE15S, ODE45,...) to solve

dy/dz = f(z,y)

with z = x/constant.

[Hassan Ghanem]

@Torsten: Thank you very much for the suggestion, it helped get things moving. I ran into the error of "undefined variable x" when I ran the code just like suggested. Any suggestions on how to troubleshoot or fix the error?

Thank you very much for all input and help!!

[Torsten]

If you don't supply the code you are using, nobody will be able to fix the error.