3.1. igraph_arpack_rssolve — ARPACK solver for symmetric matrices

3.1. `igraph_arpack_rssolve` — ARPACK solver for symmetric matrices

int igraph_arpack_rssolve(igraph_arpack_function_t *fun, void *extra,
			  igraph_arpack_options_t *options, 
			  igraph_arpack_storage_t *storage,
			  igraph_vector_t *values, igraph_matrix_t *vectors);

This is the ARPACK solver for symmetric matrices. Please use igraph_arpack_rnsolve() for non-symmetric matrices.

Arguments:

`fun`:	Pointer to an `igraph_arpack_function_t` object, the function that performs the matrix-vector multiplication.
`extra`:	An extra argument to be passed to `fun`.
`options`:	An `igraph_arpack_options_t` object.
`storage`:	An `igraph_arpack_storage_t` object, or a null pointer. In the latter case memory allocation and deallocation is performed automatically.
`values`:	If not a null pointer, then it should be a pointer to an initialized vector. The eigenvalues will be stored here. The vector will be resized as needed.
`vectors`:	If not a null pointer, then it must be a pointer to an initialized matrix. The eigenvectors will be stored in the columns of the matrix. The matrix will be resized as needed.

Returns:

Error code.

Time complexity: depends on the matrix-vector multiplication. Usually a small number of iterations is enough, so if the matrix is sparse and the matrix-vector multiplication can be done in O(n) time (the number of vertices), then the eigenvalues are found in O(n) time as well.