Hey, if you can set up your dynamical equations in explicit form: dx/dt = f(x,u) and y = g(x,u) e.g. using the symbolic math toolbox you can easily linearize your system around a steady state (x0, u0).
As an example your system matrix results from: A = jacobian(f, x) After it you need to replace all remaining x with x0 and u with u0 in A.
For the input matrix likewise shown but with B = jacobian(f,u) For C and D using g instead of f.
We published a small tool to handle nonlinear dynamical systems symbolically in MATLAB. There the feature of linearization is implemented: https://github.com/odesca/ODESCA/releases
