Intel® oneAPI Math Kernel Library Developer Reference - Fortran
Matrix arguments of BLAS routines can use the following storage schemes:
Full storage: a matrix A is stored in a two-dimensional array a, with the matrix element Aij stored in the array element a(i,j).
Packed storage scheme allows you to store symmetric, Hermitian, or triangular matrices more compactly: the upper or lower triangle of the matrix is packed by columns in a one-dimensional array.
Band storage: a band matrix is stored compactly in a two-dimensional array: columns of the matrix are stored in the corresponding columns of the array, and diagonals of the matrix are stored in rows of the array.
For more information on matrix storage schemes, see Matrix Arguments in the Appendix “Routine and Function Arguments”.