Intel® oneAPI Math Kernel Library Developer Reference - C
The symmetric and Hermitian matrices used in Extended Eigensolvers predefined interfaces can be stored in full, band, and sparse formats.
In the full storage format (described in Full Storage in additional detail) you store all elements, all of the elements in the upper triangle of the matrix, or all of the elements in the lower triangle of the matrix.
In the band storage format (described in Band storage in additional detail), you store only the elements along a diagonal band of the matrix.
In the sparse format (described in Storage Arrays for a Matrix in CSR Format (3-Array Variation)), you store only the non-zero elements of the matrix.
In generalized eigenvalue systems you must use the same family of storage format for both matrices A and B. The bandwidth can be different for the banded format (klb can be different from kla), and the position of the non-zero elements can also be different for the sparse format (CSR coordinates ib and jb can be different from ia and ja).