Note: the second dimension of the array
b
must be at least
$\mathrm{min}\phantom{\rule{0.125em}{0ex}}\left({\mathbf{m}}+{\mathbf{ku}},{\mathbf{n}}\right)$.
On entry: if
${\mathbf{job}}=\text{'U'}$,
b must contain the band matrix in packed form, in the leading
$\left({k}_{l}+{k}_{u}+1\right)$ by
$\mathrm{min}\phantom{\rule{0.125em}{0ex}}\left(m+{k}_{u},n\right)$ part of the array. The matrix is packed column by column, with the leading diagonal of the matrix in row
$\left({k}_{u}+1\right)$ of
b, the first superdiagonal starting at position
$2$ in row
${k}_{u}$, the first subdiagonal starting at position
$1$ in row
$\left({k}_{u}+2\right)$, and so on. Elements of
b that are not needed to store the band matrix, for instance the leading
${k}_{u}$ by
${k}_{u}$ triangle, are not referenced and need not be assigned.
On exit: if
${\mathbf{job}}=\text{'P'}$,
b contains the band matrix stored in packed form. Elements of
b that are not needed to store the band matrix are not referenced.