26 lines
923 B
Python
26 lines
923 B
Python
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"""subblock.py -- extract the "fully active" 9x9 sub-block M_{S->S^c} (both source and
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target sectors fully active, i.e. every party involved) from the full bigraduated
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cluster map. This is Corollary "sub-block witnesses" specialized to V=S, T=S^c."""
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import numpy as np
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def fully_active_block(C, s0, s1):
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others = [k for k in range(4) if k not in (s0, s1)]
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c0, c1 = others
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M = np.zeros((9, 9))
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rows = [(i, j) for i in [1, 2, 3] for j in [1, 2, 3]]
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cols = [(i, j) for i in [1, 2, 3] for j in [1, 2, 3]]
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for ri, (ia, ib) in enumerate(rows):
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for ci, (ic, idd) in enumerate(cols):
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idx = [0, 0, 0, 0]
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idx[s0] = ia
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idx[s1] = ib
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idx[c0] = ic
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idx[c1] = idd
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M[ri, ci] = C[tuple(idx)]
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return M / 3.0 # same normalization convention as cluster.cluster_map
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def nuc(M):
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return np.linalg.svd(M, compute_uv=False).sum()
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