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Merged
merged 8 commits into from
Jul 21, 2023
Merged

Add example for is_strongly_unimodular #5

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xuluze Jul 19, 2023
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xuluze Jul 19, 2023
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Merge branch 'cmr' into cmr_add_examples
xuluze Jul 19, 2023
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xuluze Jul 20, 2023
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Merge branch 'cmr' into cmr_add_examples
xuluze Jul 21, 2023
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add_examples_is_strongly_unimodular
xuluze Jul 21, 2023
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24 changes: 23 additions & 1 deletion src/sage/matrix/matrix_cmr_sparse.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -168,6 +168,28 @@ cdef class Matrix_cmr_chr_sparse(Matrix_cmr_sparse):
return <bint> result

def is_strongly_unimodular(self):
r"""
A matrix is strongly unimodular if ``self`` and ``self.transpose()`` are both unimodular.

EXAMPLES::

sage: from sage.matrix.matrix_cmr_sparse import Matrix_cmr_chr_sparse
sage: M = Matrix_cmr_chr_sparse(MatrixSpace(ZZ, 3, 3, sparse=True),
....: [[1, 0, 1], [0, 1, 1], [1, 2, 3]]); M
[1 0 1]
[0 1 1]
[1 2 3]
sage: M.is_unimodular()
True
sage: M.is_strongly_unimodular()
False
sage: M = Matrix_cmr_chr_sparse(MatrixSpace(ZZ, 2, 3, sparse=True),
....: [[1, 0, 0], [0, 1, 0]]); M
[1 0 0]
[0 1 0]
sage: M.is_strongly_unimodular()
True
"""
cdef bool result

sig_on()
Expand Down Expand Up @@ -295,7 +317,7 @@ cdef class Matrix_cmr_chr_sparse(Matrix_cmr_sparse):
return False, None # submatrix TBD

def is_cographic(self, *, time_limit=60.0, certificate=False):
raise NotImplementedError
raise NotImplementedError

def is_network_matrix(self, *, time_limit=60.0, certificate=False):
raise NotImplementedError
Expand Down