The skewfield
$\mathcal{K }(\partial )$ of rational pseudodifferential operators over a differential field
$\mathcal{K }$ is the skewfield of fractions of the algebra of differential operators
$\mathcal{K }[\partial ]$ . In our previous paper, we showed that any
$H\in \mathcal{K }(\partial )$ has a minimal fractional decomposition
$H=AB^{-1}$ , where
$A,B\in \mathcal{K }[\partial ],\,B\ne 0$ , and any common right divisor of
$A$ and
$B$ is a non-zero element of
$\mathcal{K }$ . Moreover, any right fractional decomposition of
$H$ is obtained by multiplying
$A$ and
$B$ on the right by the same non-zero element of
$\mathcal{K }[\partial ]$ . In the present paper, we study the ring
$M_n(\mathcal{K }(\partial ))$ of
$n\times n$ matrices over the skewfield
$\mathcal{K }(\partial )$ . We show that similarly, any
$H\in M_n(\mathcal{K }(\partial ))$ has a minimal fractional decomposition
$H=AB^{-1}$ , where
$A,B\in M_n(\mathcal{K }[\partial ]),\,B$ is non-degenerate, and any common right divisor of
$A$ and
$B$ is an invertible element of the ring
$M_n(\mathcal{K }[\partial ])$ . Moreover, any right fractional decomposition of
$H$ is obtained by multiplying
$A$ and
$B$ on the right by the same non-degenerate element of
$M_n(\mathcal{K } [\partial ])$ . We give several equivalent definitions of the minimal fractional decomposition. These results are applied to the study of maximal isotropicity property, used in the theory of Dirac structures.
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