As for me, it yields lots of inconveniences (lots of my code should be rewritten, since I didn't know it before): from numpy import * a = array((1.0, 2.0), float128) b=asfarray(a) type(a[0]) #<type 'numpy.float128'> type(b[0]) #<type 'numpy.float64'> __version__ '1.0.5.dev4767' Shouldn't it be changed? (I.e. let's left 128). As for me I use asfarray() very often since I don't know does user provide arrays as numpy ndarray or matrix or Python list/tuple. D.