To reduce the states of a system using the Krylov subspace method in MATLAB, you can utilize the balred function, as this function performs balanced truncation, which is a model reduction technique based on the Krylov subspace method.
And secon thing alway remember that balred function assumes that the system is controllable and observable, If the system does not meet these requirements, you may need to preprocess/check the system or use other techniques/methods to ensure controllability and observability before applying model reduction.
