tf = isbanded(A,lower,upper) returns
logical 1 (true) if matrix A is
within the specified lower bandwidth, lower, and
upper bandwidth, upper; otherwise, it returns logical 0 (false).

Lower bandwidth, specified as a nonnegative integer scalar.
The lower bandwidth is the number of nonzero diagonals below the main
diagonal. isbanded returns logical 0 (false)
if there are nonzero elements below the boundary diagonal, diag(A,-lower).

Upper bandwidth, specified as a nonnegative integer scalar.
The upper bandwidth is the number of nonzero diagonals above the main
diagonal. isbanded returns logical 0 (false)
if there are nonzero elements above the boundary diagonal, diag(A,upper).

Use the bandwidth function
to find the upper and lower bandwidths of a given matrix.

Use isbanded to test for several
different matrix structures by specifying appropriate upper and lower
bandwidths. The table below lists some common tests.