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@@ -0,0 +1,22 @@ |
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// Ryser's algorithm |
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static npy_complex128 perm_ryser(PyArrayObject *submatrix) { |
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int n = (int) PyArray_DIM(submatrix, 0); |
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npy_complex128 rowsum, rowsumprod; |
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npy_complex128 perm = complex_zero; |
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int exp = 1 << n; |
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int i, y, z; |
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for (i=0; i<exp; ++i) { |
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rowsumprod = complex_one; |
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for (y=0; y<n; ++y) { |
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rowsum = complex_zero; |
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for (z=0; z<n; ++z) { |
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if ((i & (1 << z)) != 0) { complex_inc(&rowsum, SM(z, y)); } |
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} |
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complex_multiply(&rowsumprod, rowsum); |
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} |
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complex_inc(&perm, complex_float_prod(rowsumprod, bitparity(i))); |
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} |
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if (n%2 == 1) {perm=complex_float_prod(perm, -1);} |
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return perm; |
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} |
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