37 lines
No EOL
1.2 KiB
Python
37 lines
No EOL
1.2 KiB
Python
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from ..core import (atleast_1d, asarray)
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from ..core.overrides import set_module
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from ulab import numpy as np
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@set_module('numpy')
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def poly(seq_of_zeros):
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seq_of_zeros = atleast_1d(seq_of_zeros)
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sh = seq_of_zeros.shape
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if len(sh) == 2 and sh[0] == sh[1] and sh[0] != 0:
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seq_of_zeros = eigvals(seq_of_zeros)
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elif len(sh) == 1:
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dt = seq_of_zeros.dtype
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# Let object arrays slip through, e.g. for arbitrary precision
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if dt != object:
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seq_of_zeros = seq_of_zeros #seq_of_zeros.astype(mintypecode(dt.char))
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else:
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raise ValueError("input must be 1d or non-empty square 2d array.")
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if len(seq_of_zeros) == 0:
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return 1.0
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dt = seq_of_zeros.dtype
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a = np.ones((1,), dtype=dt)
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for k in range(len(seq_of_zeros)):
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a = np.convolve(a, np.array([1, -seq_of_zeros[k]], dtype=dt))
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if a.dtype == np.complex:
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# if complex roots are all complex conjugates, the roots are real.
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roots = asarray(seq_of_zeros, complex)
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p = np.sort_complex(roots)
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c = np.real(p) - np.imag(p) * 1j
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q = np.sort_complex(c)
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if np.all(p == q):
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a = a.real.copy()
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return a |