obsv_mat observability matrix

## Syntax

                O = obsv_mat(sl)
                O = obsv_mat(A, C)

## Arguments

A,C,O

  real matrices

sl

  `syslin` list

## Description

`obsv_mat` returns the observability matrix:

    O=[C; CA; CA^2;...; CA^(n-1) ]

## See also

- contrss
- obsvss
- obs_gram