Symmetric, Hermitian or triangular matrices may be stored more
compactly , if the relevant
triangle (again as specified by UPLO) is packed
**by columns** in a one-dimensional array. In LAPACK, arrays that hold
matrices in packed storage, have names ending in `P'. So:

- if UPLO = `U', is stored in AP(
`i`+`j`(`j`- 1)/2) for`i`< =`j`; - if UPLO = `L', is stored in
AP(
`i`+ (2`n`-`j`)(`j`- 1)/2) for`j`< =`i`.

For example:

Note that for real or complex symmetric matrices, packing the upper triangle by columns is equivalent to packing the lower triangle by rows; packing the lower triangle by columns is equivalent to packing the upper triangle by rows. For complex Hermitian matrices, packing the upper triangle by columns is equivalent to packing the conjugate of the lower triangle by rows; packing the lower triangle by columns is equivalent to packing the conjugate of the upper triangle by rows.

Tue Nov 29 14:03:33 EST 1994