sparse.mat contains:
* a sparse matrix S
* a sparse vector v

v.mat contains:
* a vector v

collection.mat contains:
* a matrix A
* a scalar t
* a vector v
* a vector w

A.mat contains:
* a matrix A

complex.mat contains:
* dense, complex matrix a
* dense, complex matrix b
* dense, complex matrix c

sparse_complex.mat contains:
* sparse, complex matrix sa
* sparse, complex matrix sb
* sparse, complex matrix sc
