def PrestackInversion(data,
theta,
wav,
m0=None,
linearization='akirich',
explicit=False,
simultaneous=False,
epsI=None,
epsR=None,
dottest=False,
returnres=False,
epsRL1=None,
kind='centered',
**kwargs_solver):
r"""Pre-stack linearized seismic inversion.
Invert pre-stack seismic operator to retrieve a set of elastic property
profiles from band-limited seismic pre-stack data (i.e., angle gathers).
Depending on the choice of input parameters, inversion can be
trace-by-trace with explicit operator or global with either
explicit or linear operator.
Parameters
----------
data : :obj:`np.ndarray`
Band-limited seismic post-stack data of size
:math:`[(n_{lins} \times) n_{t0} \times n_{\theta} (\times n_x \times n_y)]`
theta : :obj:`np.ndarray`
Incident angles in degrees
wav : :obj:`np.ndarray`
Wavelet in time domain (must had odd number of elements
and centered to zero)
m0 : :obj:`np.ndarray`, optional
Background model of size :math:`[n_{t0} \times n_{m}
(\times n_x \times n_y)]`
linearization : :obj:`str` or :obj:`list`, optional
choice of linearization, ``akirich``: Aki-Richards, ``fatti``: Fatti
``PS``: PS or a combination of them (required only when ``m0``
is ``None``).
explicit : :obj:`bool`, optional
Create a chained linear operator (``False``, preferred for large data)
or a ``MatrixMult`` linear operator with dense matrix
(``True``, preferred for small data)
simultaneous : :obj:`bool`, optional
Simultaneously invert entire data (``True``) or invert
trace-by-trace (``False``) when using ``explicit`` operator
(note that the entire data is always inverted when working
with linear operator)
epsI : :obj:`float` or :obj:`list`, optional
Damping factor(s) for Tikhonov regularization term. If a list of
:math:`n_{m}` elements is provided, the regularization term will have
different strenght for each elastic property
epsR : :obj:`float`, optional
Damping factor for additional Laplacian regularization term
dottest : :obj:`bool`, optional
Apply dot-test
returnres : :obj:`bool`, optional
Return residuals
epsRL1 : :obj:`float`, optional
Damping factor for additional blockiness regularization term
kind : :obj:`str`, optional
Derivative kind (``forward`` or ``centered``).
**kwargs_solver
Arbitrary keyword arguments for :py:func:`scipy.linalg.lstsq`
solver (if ``explicit=True`` and ``epsR=None``)
or :py:func:`scipy.sparse.linalg.lsqr` solver (if ``explicit=False``
and/or ``epsR`` is not ``None``))
Returns
-------
minv : :obj:`np.ndarray`
Inverted model of size :math:`[n_{t0} \times n_{m}
(\times n_x \times n_y)]`
datar : :obj:`np.ndarray`
Residual data (i.e., data - background data) of
size :math:`[n_{t0} \times n_{\theta} (\times n_x \times n_y)]`
Notes
-----
The different choices of cost functions and solvers used in the
seismic pre-stack inversion module follow the same convention of the
seismic post-stack inversion module.
Refer to :py:func:`pylops.avo.poststack.PoststackInversion` for
more details.
"""
ncp = get_array_module(data)
# find out dimensions
if m0 is None and linearization is None:
raise NotImplementedError('either m0 or linearization '
'must be provided')
elif m0 is None:
if isinstance(linearization, str):
nm = _linearizations[linearization]
else:
nm = _linearizations[linearization[0]]
else:
nm = m0.shape[1]
data_shape = data.shape
data_ndim = data.ndim
n_lins = 1
multi = 0
if not isinstance(linearization, str):
n_lins = data_shape[0]
data_shape = data_shape[1:]
data_ndim -= 1
multi = 1
if data_ndim == 2:
dims = 1
nt0, ntheta = data_shape
nspat = None
nspatprod = nx = 1
elif data_ndim == 3:
dims = 2
nt0, ntheta, nx = data_shape
nspat = (nx, )
nspatprod = nx
else:
dims = 3
nt0, ntheta, nx, ny = data_shape
nspat = (nx, ny)
nspatprod = nx * ny
data = data.reshape(nt0, ntheta, nspatprod)
# check if background model and data have same shape
if m0 is not None:
if nt0 != m0.shape[0] or\
(dims >= 2 and nx != m0.shape[2]) or\
(dims == 3 and ny != m0.shape[3]):
raise ValueError('data and m0 must have same time and space axes')
# create operator
if isinstance(linearization, str):
# single operator
PPop = PrestackLinearModelling(wav,
theta,
nt0=nt0,
spatdims=nspat,
linearization=linearization,
explicit=explicit,
kind=kind)
else:
# multiple operators
if not isinstance(wav, (list, tuple)):
wav = [
wav,
] * n_lins
PPop = [
PrestackLinearModelling(w,
theta,
nt0=nt0,
spatdims=nspat,
linearization=lin,
explicit=explicit)
for w, lin in zip(wav, linearization)
]
if explicit:
PPop = MatrixMult(np.vstack([Op.A for Op in PPop]),
dims=nspat,
dtype=PPop[0].A.dtype)
else:
PPop = VStack(PPop)
if dottest:
Dottest(PPop,
n_lins * nt0 * ntheta * nspatprod,
nt0 * nm * nspatprod,
raiseerror=True,
verb=True,
backend=get_module_name(ncp))
# swap axes for explicit operator
if explicit:
data = data.swapaxes(0 + multi, 1 + multi)
if m0 is not None:
m0 = m0.swapaxes(0, 1)
# invert model
if epsR is None:
# create and remove background data from original data
datar = data.flatten() if m0 is None else \
data.flatten() - PPop * m0.flatten()
# inversion without spatial regularization
if explicit:
if epsI is None and not simultaneous:
# solve unregularized equations indipendently trace-by-trace
minv = \
get_lstsq(data)(PPop.A,
datar.reshape(n_lins*nt0*ntheta, nspatprod).squeeze(),
**kwargs_solver)[0]
elif epsI is None and simultaneous:
# solve unregularized equations simultaneously
if ncp == np:
minv = lsqr(PPop, datar, **kwargs_solver)[0]
else:
minv = cgls(PPop,
datar,
x0=ncp.zeros(int(PPop.shape[1]), PPop.dtype),
**kwargs_solver)[0]
elif epsI is not None:
# create regularized normal equations
PP = ncp.dot(PPop.A.T, PPop.A) + \
epsI * ncp.eye(nt0*nm, dtype=PPop.A.dtype)
datarn = np.dot(PPop.A.T,
datar.reshape(nt0 * ntheta, nspatprod))
if not simultaneous:
# solve regularized normal eqs. trace-by-trace
minv = get_lstsq(data)(PP, datarn, **kwargs_solver)[0]
else:
# solve regularized normal equations simultaneously
PPop_reg = MatrixMult(PP, dims=nspatprod)
if ncp == np:
minv = lsqr(PPop_reg, datarn.ravel(),
**kwargs_solver)[0]
else:
minv = cgls(PPop_reg,
datarn.ravel(),
x0=ncp.zeros(int(PPop_reg.shape[1]),
PPop_reg.dtype),
**kwargs_solver)[0]
#else:
# # create regularized normal eqs. and solve them simultaneously
# PP = np.dot(PPop.A.T, PPop.A) + epsI * np.eye(nt0*nm)
# datarn = PPop.A.T * datar.reshape(nt0*ntheta, nspatprod)
# PPop_reg = MatrixMult(PP, dims=ntheta*nspatprod)
# minv = lstsq(PPop_reg, datarn.flatten(), **kwargs_solver)[0]
else:
# solve unregularized normal equations simultaneously with lop
if ncp == np:
minv = lsqr(PPop, datar, **kwargs_solver)[0]
else:
minv = cgls(PPop,
datar,
x0=ncp.zeros(int(PPop.shape[1]), PPop.dtype),
**kwargs_solver)[0]
else:
# Create Thicknov regularization
if epsI is not None:
if isinstance(epsI, (list, tuple)):
if len(epsI) != nm:
raise ValueError('epsI must be a scalar or a list of'
'size nm')
RegI = Diagonal(np.array(epsI),
dims=(nt0, nm, nspatprod),
dir=1)
else:
RegI = epsI * Identity(nt0 * nm * nspatprod)
if epsRL1 is None:
# L2 inversion with spatial regularization
if dims == 1:
Regop = SecondDerivative(nt0 * nm,
dtype=PPop.dtype,
dims=(nt0, nm))
elif dims == 2:
Regop = Laplacian((nt0, nm, nx), dirs=(0, 2), dtype=PPop.dtype)
else:
Regop = Laplacian((nt0, nm, nx, ny),
dirs=(2, 3),
dtype=PPop.dtype)
if epsI is None:
Regop = (Regop, )
epsR = (epsR, )
else:
Regop = (Regop, RegI)
epsR = (epsR, 1)
minv = \
RegularizedInversion(PPop, Regop, data.ravel(),
x0=m0.flatten() if m0 is not None
else None, epsRs=epsR,
returninfo=False, **kwargs_solver)
else:
# Blockiness-promoting inversion with spatial regularization
if dims == 1:
RegL1op = FirstDerivative(nt0 * nm, dtype=PPop.dtype)
RegL2op = None
elif dims == 2:
RegL1op = FirstDerivative(nt0 * nx * nm,
dims=(nt0, nm, nx),
dir=0,
dtype=PPop.dtype)
RegL2op = SecondDerivative(nt0 * nx * nm,
dims=(nt0, nm, nx),
dir=2,
dtype=PPop.dtype)
else:
RegL1op = FirstDerivative(nt0 * nx * ny * nm,
dims=(nt0, nm, nx, ny),
dir=0,
dtype=PPop.dtype)
RegL2op = Laplacian((nt0, nm, nx, ny),
dirs=(2, 3),
dtype=PPop.dtype)
if dims == 1:
if epsI is not None:
RegL2op = (RegI, )
epsR = (1, )
else:
if epsI is None:
RegL2op = (RegL2op, )
epsR = (epsR, )
else:
RegL2op = (RegL2op, RegI)
epsR = (epsR, 1)
epsRL1 = (epsRL1, )
if 'mu' in kwargs_solver.keys():
mu = kwargs_solver['mu']
kwargs_solver.pop('mu')
else:
mu = 1.
if 'niter_outer' in kwargs_solver.keys():
niter_outer = kwargs_solver['niter_outer']
kwargs_solver.pop('niter_outer')
else:
niter_outer = 3
if 'niter_inner' in kwargs_solver.keys():
niter_inner = kwargs_solver['niter_inner']
kwargs_solver.pop('niter_inner')
else:
niter_inner = 5
minv = SplitBregman(PPop, (RegL1op, ),
data.ravel(),
RegsL2=RegL2op,
epsRL1s=epsRL1,
epsRL2s=epsR,
mu=mu,
niter_outer=niter_outer,
niter_inner=niter_inner,
x0=None if m0 is None else m0.flatten(),
**kwargs_solver)[0]
# compute residual
if returnres:
if epsR is None:
datar -= PPop * minv.ravel()
else:
datar = data.ravel() - PPop * minv.ravel()
# re-swap axes for explicit operator
if explicit:
if m0 is not None:
m0 = m0.swapaxes(0, 1)
# reshape inverted model and residual data
if dims == 1:
if explicit:
minv = minv.reshape(nm, nt0).swapaxes(0, 1)
if returnres:
datar = datar.reshape(n_lins, ntheta, nt0).squeeze().swapaxes(
0 + multi, 1 + multi)
else:
minv = minv.reshape(nt0, nm)
if returnres:
datar = datar.reshape(n_lins, nt0, ntheta).squeeze()
elif dims == 2:
if explicit:
minv = minv.reshape(nm, nt0, nx).swapaxes(0, 1)
if returnres:
datar = datar.reshape(n_lins, ntheta, nt0,
nx).squeeze().swapaxes(
0 + multi, 1 + multi)
else:
minv = minv.reshape(nt0, nm, nx)
if returnres:
datar = datar.reshape(n_lins, nt0, ntheta, nx).squeeze()
else:
if explicit:
minv = minv.reshape(nm, nt0, nx, ny).swapaxes(0, 1)
if returnres:
datar = datar.reshape(n_lins, ntheta, nt0, nx,
ny).squeeze().swapaxes(
0 + multi, 1 + multi)
else:
minv = minv.reshape(nt0, nm, nx, ny)
if returnres:
datar = datar.reshape(n_lins, nt0, ntheta, nx, ny).squeeze()
if m0 is not None and epsR is None:
minv = minv + m0
if returnres:
return minv, datar
else:
return minv
def apply_multiplepoints(self,
trav,
G0=None,
nfft=None,
rtm=False,
greens=False,
dottest=False,
**kwargs_lsqr):
r"""Marchenko redatuming for multiple points
Solve the Marchenko redatuming inverse problem for multiple points given
their direct arrival traveltime curves (``trav``) and waveforms (``G0``).
Parameters
----------
trav : :obj:`numpy.ndarray`
Traveltime of first arrival from subsurface points to surface receivers
of size :math:`[n_r \times n_{vs}]`
G0 : :obj:`numpy.ndarray`, optional
Direct arrival in time domain of size :math:`[n_r \times n_{vs} \times n_t]`
(if None, create arrival using ``trav``)
nfft : :obj:`int`, optional
Number of samples in fft when creating the analytical direct wave
rtm : :obj:`bool`, optional
Compute and return rtm redatuming
greens : :obj:`bool`, optional
Compute and return Green's functions
dottest : :obj:`bool`, optional
Apply dot-test
**kwargs_lsqr
Arbitrary keyword arguments for :py:func:`scipy.sparse.linalg.lsqr` solver
Returns
----------
f1_inv_minus : :obj:`numpy.ndarray`
Inverted upgoing focusing function of size :math:`[n_r \times n_{vs} \times n_t]`
f1_inv_plus : :obj:`numpy.ndarray`
Inverted downgoing focusing functionof size :math:`[n_r \times n_{vs} \times n_t]`
p0_minus : :obj:`numpy.ndarray`
Single-scattering standard redatuming upgoing Green's function
of size :math:`[n_r \times n_{vs} \times n_t]`
g_inv_minus : :obj:`numpy.ndarray`
Inverted upgoing Green's function of size :math:`[n_r \times n_{vs} \times n_t]`
g_inv_plus : :obj:`numpy.ndarray`
Inverted downgoing Green's function of size :math:`[n_r \times n_{vs} \times n_t]`
"""
nvs = trav.shape[1]
# Create window
trav_off = trav - self.toff
trav_off = np.round(trav_off / self.dt).astype(np.int)
w = np.zeros((self.nr, nvs, self.nt))
for ir in range(self.nr):
for ivs in range(nvs):
w[ir, ivs, :trav_off[ir, ivs]] = 1
w = np.concatenate((np.flip(w, axis=-1), w[:, :, 1:]), axis=-1)
if self.nsmooth > 0:
smooth = np.ones(self.nsmooth) / self.nsmooth
w = filtfilt(smooth, 1, w)
# Create operators
Rop = MDC(self.Rtwosided_fft,
self.nt2,
nv=nvs,
dt=self.dt,
dr=self.dr,
twosided=True,
dtype=self.dtype)
R1op = MDC(self.R1twosided_fft,
self.nt2,
nv=nvs,
dt=self.dt,
dr=self.dr,
twosided=True,
dtype=self.dtype)
Wop = Diagonal(w.flatten())
Iop = Identity(self.nr * nvs * (2 * self.nt - 1))
Mop = VStack(
[HStack([Iop, -1 * Wop * Rop]),
HStack([-1 * Wop * R1op, Iop])]) * BlockDiag([Wop, Wop])
Gop = VStack([HStack([Iop, -1 * Rop]), HStack([-1 * R1op, Iop])])
if dottest:
assert Dottest(Gop,
2 * self.nr * nvs * self.nt2,
2 * self.nr * nvs * self.nt2,
verb=True)
if dottest:
assert Dottest(Mop,
2 * self.nr * nvs * self.nt2,
2 * self.nr * nvs * self.nt2,
verb=True)
# Create input focusing function
if G0 is None:
if self.wav is not None and nfft is not None:
G0 = np.zeros((self.nr, nvs, self.nt))
for ivs in range(nvs):
G0[:, ivs] = (directwave(self.wav,
trav[:, ivs],
self.nt,
self.dt,
nfft=nfft)).T
else:
logging.error('wav and/or nfft are not provided. '
'Provide either G0 or wav and nfft...')
raise ValueError('wav and/or nfft are not provided. '
'Provide either G0 or wav and nfft...')
fd_plus = np.concatenate(
(np.flip(G0, axis=-1), np.zeros((self.nr, nvs, self.nt - 1))),
axis=-1)
# Run standard redatuming as benchmark
if rtm:
p0_minus = Rop * fd_plus.flatten()
p0_minus = p0_minus.reshape(self.nr, nvs, self.nt2)
# Create data and inverse focusing functions
d = Wop * Rop * fd_plus.flatten()
d = np.concatenate(
(d.reshape(self.nr, nvs,
self.nt2), np.zeros((self.nr, nvs, self.nt2))))
f1_inv = lsqr(Mop, d.flatten(), **kwargs_lsqr)[0]
f1_inv = f1_inv.reshape(2 * self.nr, nvs, self.nt2)
f1_inv_tot = f1_inv + np.concatenate((np.zeros(
(self.nr, nvs, 2 * self.nt - 1)), fd_plus))
f1_inv_minus, f1_inv_plus = f1_inv_tot[:self.nr], f1_inv_tot[self.nr:]
if greens:
# Create Green's functions
g_inv = Gop * f1_inv_tot.flatten()
g_inv = g_inv.reshape(2 * self.nr, nvs, (2 * self.nt - 1))
g_inv_minus, g_inv_plus = -g_inv[:self.nr], np.flip(
g_inv[self.nr:], axis=-1)
if rtm and greens:
return f1_inv_minus, f1_inv_plus, p0_minus, g_inv_minus, g_inv_plus
elif rtm:
return f1_inv_minus, f1_inv_plus, p0_minus
elif greens:
return f1_inv_minus, f1_inv_plus, g_inv_minus, g_inv_plus
else:
return f1_inv_minus, f1_inv_plus
def PrestackWaveletModelling(m,
theta,
nwav,
wavc=None,
vsvp=0.5,
linearization='akirich'):
r"""Pre-stack linearized seismic modelling operator for wavelet.
Create operator to be applied to a wavelet for generation of
band-limited seismic angle gathers using a linearized version
of the Zoeppritz equation.
Parameters
----------
m : :obj:`np.ndarray`
elastic parameter profles of size :math:`[n_{t0} \times N]`
where :math:`N=3/2`. Note that the ``dtype`` of this
variable will define that of the operator
theta : :obj:`int`
Incident angles in degrees. Must have same ``dtype`` of ``m`` (or
it will be automatically casted to it)
nwav : :obj:`np.ndarray`
Number of samples of wavelet to be applied/estimated
wavc : :obj:`int`, optional
Index of the center of the wavelet
vsvp : :obj:`np.ndarray` or :obj:`float`, optional
VS/VP ratio
linearization : :obj:`str`, optional
choice of linearization, ``akirich``: Aki-Richards,
``fatti``: Fatti, ``ps``: PS, or any function on the form of
``pylops.avo.avo.akirichards``
Returns
-------
Mconv : :obj:`LinearOperator`
pre-stack modelling operator for wavelet estimation.
Raises
------
NotImplementedError
If ``linearization`` is not an implemented linearization
Notes
-----
Pre-stack seismic modelling for wavelet estimate is the process
of constructing seismic reflectivities using three (or two)
profiles of elastic parameters in time (or depth)
domain arranged in an input vector :math:`\mathbf{m}`
of size :math:`nt0 \times N`:
.. math::
d(t, \theta) = \sum_{i=1}^N G_i(t, \theta) m_i(t) * w(t)
where :math:`w(t)` is the time domain seismic wavelet. In compact form:
.. math::
\mathbf{d}= \mathbf{G} \mathbf{w}
On the other hand, pre-stack wavelet estimation aims at
recovering the wavelet given knowledge of the band-limited
seismic pre-stack data and the elastic parameter profiles.
"""
ncp = get_array_module(theta)
# define dtype to be used
dtype = m.dtype # ensure m.dtype rules that of operator
theta = theta.astype(dtype)
# Create vsvp profile
vsvp = vsvp if isinstance(vsvp, ncp.ndarray) else \
vsvp * ncp.ones(m.shape[0], dtype=dtype)
wavc = nwav // 2 if wavc is None else wavc
nt0 = len(vsvp)
ntheta = len(theta)
# Create AVO operator
if linearization == 'akirich':
G = akirichards(theta, vsvp, n=nt0)
elif linearization == 'fatti':
G = fatti(theta, vsvp, n=nt0)
elif linearization == 'ps':
G = ps(theta, vsvp, n=nt0)
elif callable(linearization):
G = linearization(theta, vsvp, n=nt0)
else:
logging.error('%s not an available linearization...', linearization)
raise NotImplementedError('%s not an available linearization...' %
linearization)
nG = len(G)
G = [
ncp.hstack(
[ncp.diag(G_[itheta] * ncp.ones(nt0, dtype=dtype)) for G_ in G])
for itheta in range(ntheta)
]
G = ncp.vstack(G).reshape(ntheta * nt0, nG * nt0)
# Create derivative operator
D = ncp.diag(0.5 * np.ones(nt0 - 1, dtype=dtype), k=1) - \
ncp.diag(0.5 * np.ones(nt0 - 1, dtype=dtype), k=-1)
D[0] = D[-1] = 0
D = get_block_diag(theta)(*([D] * nG))
# Create infinite-reflectivity data
M = ncp.dot(G, ncp.dot(D, m.T.flatten())).reshape(ntheta, nt0)
Mconv = VStack([
MatrixMult(convmtx(M[itheta], nwav)[wavc:-nwav + wavc + 1],
dtype=dtype) for itheta in range(ntheta)
])
return Mconv
def PrestackWaveletModelling(m,
theta,
nwav,
wavc=None,
vsvp=0.5,
linearization='akirich'):
r"""Pre-stack linearized seismic modelling operator for wavelet.
Create operator to be applied to a wavelet for generation of
band-limited seismic angle gathers using a linearized version
of the Zoeppritz equation.
Parameters
----------
m : :obj:`np.ndarray`
elastic parameter profles of size :math:`[n_{t0} \times N]`
where :math:`N=3/2`
theta : :obj:`int`
Incident angles in degrees
nwav : :obj:`np.ndarray`
Number of samples of wavelet to be applied/estimated
wavc : :obj:`int`, optional
Index of the center of the wavelet
vsvp : :obj:`np.ndarray` or :obj:`float`, optional
VS/VP ratio
linearization : :obj:`str`, optional
choice of linearization, ``akirich``: Aki-Richards,
``fatti``: Fatti
Returns
-------
Mconv : :obj:`LinearOperator`
pre-stack modelling operator for wavelet estimation.
Raises
------
NotImplementedError
If ``linearization`` is not an implemented linearization
Notes
-----
Pre-stack seismic modelling for wavelet estimate is the process
of constructing seismic reflectivities using three (or two)
profiles of elastic parameters in time (or depth)
domain arranged in an input vector :math:`\mathbf{m}`
of size :math:`nt0 \times N`:
.. math::
d(t, \theta) = \sum_{i=1}^N G_i(t, \theta) m_i(t) * w(t)
where :math:`w(t)` is the time domain seismic wavelet. In compact form:
.. math::
\mathbf{d}= \mathbf{G} \mathbf{w}
On the other hand, pre-stack wavelet estimation aims at
recovering the wavelet given knowledge of the band-limited
seismic pre-stack data and the elastic parameter profiles.
"""
# Create vsvp profile
vsvp = vsvp if isinstance(vsvp, np.ndarray) else vsvp * np.ones(m.shape[0])
wavc = nwav // 2 if wavc is None else wavc
nt0 = len(vsvp)
ntheta = len(theta)
# Create derivative operator
D = np.diag(0.5 * np.ones(nt0 - 1), k=1) - \
np.diag(0.5 * np.ones(nt0 - 1), -1)
D[0] = D[-1] = 0
D = block_diag(*([D] * 3))
# Create AVO operator
if linearization == 'akirich':
G1, G2, G3 = akirichards(theta, vsvp, n=nt0)
elif linearization == 'fatti':
G1, G2, G3 = fatti(theta, vsvp, n=nt0)
else:
logging.error('%s not an available linearization...', linearization)
raise NotImplementedError('%s not an available linearization...' %
linearization)
G = [
np.hstack((np.diag(G1[itheta] * np.ones(nt0)),
np.diag(G2[itheta] * np.ones(nt0)),
np.diag(G3[itheta] * np.ones(nt0))))
for itheta in range(ntheta)
]
G = np.vstack(G).reshape(ntheta * nt0, 3 * nt0)
# Create infinite-reflectivity data
M = np.dot(G, np.dot(D, m.T.flatten())).reshape(ntheta, nt0)
Mconv = VStack([
MatrixMult(convmtx(M[itheta], nwav)[wavc:-nwav + wavc + 1])
for itheta in range(ntheta)
])
return Mconv