Shape Error in chapter16_tensor_methods

[thomelane]

When running mxnet-the-straight-dope/chapter16_tensor_methods/tensor_basics.ipynb, all works up until line res = mode_dot(X, M, mode=1) (Cell 18) when get the stack trace below.

---------------------------------------------------------------------------
MXNetError                                Traceback (most recent call last)
<ipython-input-18-59009149ac70> in <module>()
----> 1 res = mode_dot(X, M, mode=1)

<ipython-input-16-55598ff29592> in mode_dot(tensor, matrix_or_vector, mode)
     35 
     36     # refold the result into a tensor and return it
---> 37     return fold(res, fold_mode, new_shape)

<ipython-input-14-1bfd1880eb89> in fold(unfolded_tensor, mode, shape)
     19     mode_dim = full_shape.pop(mode)
     20     full_shape.insert(0, mode_dim)
---> 21     return nd.moveaxis(nd.reshape(unfolded_tensor, full_shape), 0, mode)

~/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/ndarray/register.py in reshape(data, shape, reverse, target_shape, keep_highest, out, name, **kwargs)

~/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/_ctypes/ndarray.py in _imperative_invoke(handle, ndargs, keys, vals, out)
     90         c_str_array(keys),
     91         c_str_array([str(s) for s in vals]),
---> 92         ctypes.byref(out_stypes)))
     93 
     94     if original_output is not None:

~/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/base.py in check_call(ret)
    147     """
    148     if ret != 0:
--> 149         raise MXNetError(py_str(_LIB.MXGetLastError()))
    150 
    151 

MXNetError: [23:58:13] src/operator/tensor/./matrix_op-inl.h:187: Check failed: oshape.Size() == dshape.Size() (24 vs. 30) Target shape size is different to source. Target: [4,3,2]
Source: [5,6]

Stack trace returned 10 entries:
[bt] (0) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/libmxnet.so(+0x30cbe2) [0x7f4eb095bbe2]
[bt] (1) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/libmxnet.so(+0x30d1b8) [0x7f4eb095c1b8]
[bt] (2) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/libmxnet.so(+0x27cd55f) [0x7f4eb2e1c55f]
[bt] (3) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/libmxnet.so(+0x29bf312) [0x7f4eb300e312]
[bt] (4) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/libmxnet.so(+0x29c8dee) [0x7f4eb3017dee]
[bt] (5) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/libmxnet.so(+0x2900c4b) [0x7f4eb2f4fc4b]
[bt] (6) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/site-packages/mxnet/libmxnet.so(MXImperativeInvokeEx+0x6f) [0x7f4eb2f5020f]
[bt] (7) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/lib-dynload/../../libffi.so.6(ffi_call_unix64+0x4c) [0x7f4f0c06cec0]
[bt] (8) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/lib-dynload/../../libffi.so.6(ffi_call+0x22d) [0x7f4f0c06c87d]
[bt] (9) /home/ubuntu/anaconda3/envs/mxnet_p36/lib/python3.6/lib-dynload/_ctypes.cpython-36m-x86_64-linux-gnu.so(_ctypes_callproc+0x2ce) [0x7f4f0c281dee]