7

Para un sistema variante con el tiempo se escribiría ${\mathbf{\dot x}} = {\mathbf{f}}\left( {{\mathbf{x}}\left( t \right),{\mathbf{u}}\left( t \right),t} \right){\text{ e}}\,\,\,{\mathbf{y}}\left( t \right) = {\mathbf{h}}\left( {{\mathbf{x}}\left( t \right){\text{,}}{\mathbf{u}}\left( t \right),t} \right).\,\,\,\,\,\,\,\,\,\,\,$