<s>
In	O
mathematics	O
,	O
a	O
-matrix	O
is	O
a	O
complex	O
square	B-Algorithm
matrix	I-Algorithm
with	O
every	O
principal	O
minor	O
is	O
positive	O
.	O
</s>
<s>
The	O
class	O
of	O
nonsingular	O
M-matrices	B-Algorithm
is	O
a	O
subset	O
of	O
the	O
class	O
of	O
-matrices	O
.	O
</s>
