Source code for cr.sparse._src.lop.special_matrices

# Copyright 2021 CR-Suite Development Team
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# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
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#     https://www.apache.org/licenses/LICENSE-2.0
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import math
import jax.numpy as jnp

from .impl import _hermitian
from .lop import Operator
from .util import apply_along_axis


[docs]def circulant(n, c, axis=0): """Circulant matrix operator """ r = len(c) assert n >= r c_padded = jnp.pad(c, (0, n-r)) cf = jnp.fft.rfft(c_padded, n=n) c_j = jnp.roll(c_padded[::-1], 1) cjf = jnp.fft.rfft(c_j, n=n) times = lambda x : jnp.fft.irfft(jnp.fft.rfft(x, n=n) * cf, n=n) trans = lambda x : jnp.fft.irfft(jnp.fft.rfft(x, n=n) * cjf, n=n) times, trans = apply_along_axis(times, trans, axis) return Operator(times=times, trans=trans, shape=(n,n))