which are slightly smaller than their corresponding sparse vectors.  So I changed
the requires clause of the dot(sparse,dense) and dot(dense,sparse) functions to not
require that the dense vector's size > sparse vector's size.  Now any combination
of sizes is legal.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%404181