A square matrix with determinant . Sometimes when considering matrices over a commutative ring one understands by a unimodular matrix an invertible matrix.
Often also a unimodular matrix is meant to have determinant . The unimodular matrices, in any of the meanings, form a group under multiplication. Cf. also Unimodular transformation.
Unimodular matrix. O.A. Ivanova (originator), Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Unimodular_matrix&oldid=15584