Class transforming any matrix to bi-diagonal shape.
Any m × n matrix A can be written as the product of three matrices: A = U × B × VT with U an m × m orthogonal matrix, B an m × n bi-diagonal matrix (lower diagonal if m < n, upper diagonal otherwise), and V an n × n orthogonal matrix.
Transformation to bi-diagonal shape is often not a goal by itself, but it is an intermediate step in more general decomposition algorithms like {@link SingularValueDecomposition Singular Value Decomposition}. This class is therefore intended for internal use by the library and is not public. As a consequence of this explicitly limited scope, many methods directly returns references to internal arrays, not copies.
@since 2.0