opBinary Binary (0/1) ensemble.
opBinary(M,N) creates an M-by-N binary-ensemble operator.
opBinary(M) creates a square M-by-B binary-ensemble.
opGaussian(M,N,MODE) is the same as above, except that the
parameter MODE controls the type of ensemble that is generated.
The default is MODE=0 unless the overall memory requred exceeds 50
MODE = 0 (default): generates an explicit matrix with O(M*N)
MODE = 1: generates columns of the matrix as the operator is
applied. This allows for much larger ensembles because the matrix
is stored implicitly. The overall storage is O(M).