Hi, the kron(a,b) function seems to allow shapes such as (0,x) or (y,0) only for the second argument b, not for the first argument a. (See below for examples.) Maybe it's too harsh to call it a bug because the result is typically not defined mathematically. But then why differentiate between allowing those things for b (very useful), but not for a (thus requiring workarounds.) Thanks for your help, Sven
n.kron(n.ones((0,1)), n.ones((1,1))) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python2.5/site-packages/numpy/lib/shape_base.py", line 572, in kron result = concatenate(result, axis=axis) ValueError: concatenation of zero-length sequences is impossible n.kron(n.ones((1,0)), n.ones((1,1))) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python2.5/site-packages/numpy/lib/shape_base.py", line 572, in kron result = concatenate(result, axis=axis) ValueError: concatenation of zero-length sequences is impossible n.kron(n.ones((1,1)), n.ones((0,1))) array([], shape=(0, 1), dtype=float64) n.kron(n.ones((1,1)), n.ones((1,0))) array([], shape=(1, 0), dtype=float64) n.__version__ '1.0.1'