This is a wrapper for general dense or sparse dot products. It is only necessary as a common interface for supporting ndarray, scipy spmatrix, and PySparse arrays.

Returns a dense (1 x n) vector with the column averages of A, which can be an (m x n) sparse or dense matrix.

>>> a = numpy.array([[1,2],[3,4]],'d')
>>> columnmeans(a)
array([ 2.,  3.])