Important: The linalg package has been deprecated. Use the superseding command LinearAlgebra[BandMatrix], instead.

- For information on migrating linalg code to the new packages, see examples/LinearAlgebraMigration.

The call band(b, n) creates an n x n banded matrix using the elements of b. The number of elements of b must be odd and not greater than 2*n-1.

If b has n elements, the middle n diagonals of the result are initialized to the elements of b, in left-to-right order. In each diagonal all elements have the same value.

If 2*n-1 is larger than the length of b, then the remaining sub- and super-diagonals are set to zero.

The matrix result uses a sparse indexing function.

The command with(linalg,band) allows the use of the abbreviated form of this command.

$\mathrm{with}\left(\mathrm{linalg}\right)\:$

$\mathrm{band}\left(\left[1\right]\,3\right)$

$\left[\begin{array}{ccc}1& 0& 0\\ 0& 1& 0\\ 0& 0& 1\end{array}\right]$

$\mathrm{band}\left(\left[1\,2\,-1\right]\,4\right)$

$\left[\begin{array}{cccc}2& \mathrm{-1}& 0& 0\\ 1& 2& \mathrm{-1}& 0\\ 0& 1& 2& \mathrm{-1}\\ 0& 0& 1& 2\end{array}\right]$