I'd like to form some tensor products of sparse matrices, but this does not
seem to work:
from sympy import diag
from sympy.physics.quantum import TensorProduct
from sympy.matrices import SparseMatrix
spm = SparseMatrix(diag(1,0))
tp = TensorProduct(spm,spm)
Here's the failure:
Traceback (most recent call last):
File
"/Users/ddahl/anaconda3/envs/qiskit/lib/python3.8/site-packages/IPython/core/interactiveshell.py",
line 3331, in run_code
exec(code_obj, self.user_global_ns, self.user_ns)
File "<ipython-input-9-88417d1a4157>", line 1, in <module>
tp = TensorProduct(spm,spm)
File
"/Users/ddahl/anaconda3/envs/qiskit/lib/python3.8/site-packages/sympy/physics/quantum/tensorproduct.py",
line 123, in __new__
c_part, new_args = cls.flatten(sympify(args))
File
"/Users/ddahl/anaconda3/envs/qiskit/lib/python3.8/site-packages/sympy/physics/quantum/tensorproduct.py",
line 139, in flatten
cp, ncp = arg.args_cnc()
File
"/Users/ddahl/anaconda3/envs/qiskit/lib/python3.8/site-packages/sympy/matrices/matrices.py",
line 2339, in __getattr__
raise AttributeError(
AttributeError: ImmutableSparseMatrix has no attribute args_cnc.
When I look in sympy/physics/quantum/tensorproduct.py it looks to me like
there is an attempted test to determine
whether the first argument to the TensorProduct(...) function is a sparse
SciPy matrix:
def __new__(cls, *args):
if isinstance(args[0], (Matrix, numpy_ndarray, scipy_sparse_matrix)):
return matrix_tensor_product(*args)
c_part, new_args = cls.flatten(sympify(args))
c_part = Mul(*c_part)
if len(new_args) == 0:
return c_part
elif len(new_args) == 1:
return c_part * new_args[0]
else:
tp = Expr.__new__(cls, *new_args)
return c_part * tp
But according to my debugger, the isinstance(...) call in the above code
block returns false.
Looks to me like that sparse matrix should be of type scipy_sparse_matrix.
My environment is a freshly built Anaconda from two weeks ago and I'm
running on macOS.
What am I missing?
Thanks,
-Denny
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