A BasicSeries is a SortedMap with:
Sligthly restricted type parameters
The option to set a name and colour
A few additional methods to help access and modify series entries
A general matrix [A] (m-by-n) can be factorized by similarity
transformations into the form [A]=[Q1][D][Q2]T where
[D] (r-by-r) is (upper or lower) bidiagonal
[Q1] (m-by-r) is orthogonal
[Q2] (n-by-r) is orthogonal
r = min(m,n)