IsBidiagonal
Tests if a matrix is bidiagonal.
Syntax

IsBidiagonal(A[, ε])

A
is a matrix 
ε
is a positive number

Description
If A
is a matrix then IsBidiagonal(A, ε)
is true
iff A
is upper bidiagonal or lower bidiagonal (with epsilon ε
).
Examples
❨❨1, 2, 0, 0❩, ❨0, 2, 3, 0❩, ❨0, 0, 1, 0❩, ❨0, 0, 0, 5❩❩
⎛1 2 0 0⎞ ⎜0 2 3 0⎟ ⎜0 0 1 0⎟ ⎝0 0 0 5⎠
IsBidiagonal(ans)
true