pylops.VStack#
- class pylops.VStack(ops, nproc=1, forceflat=None, dtype=None)[source]#
Vertical stacking.
Stack a set of N linear operators vertically.
- Parameters
- ops
list
Linear operators to be stacked. Alternatively,
numpy.ndarray
orscipy.sparse
matrices can be passed in place of one or more operators.- nproc
int
, optional Number of processes used to evaluate the N operators in parallel using
multiprocessing
. Ifnproc=1
, work in serial mode.- forceflat
bool
, optional New in version 2.2.0.
Force an array to be flattened after rmatvec.
- dtype
str
, optional Type of elements in input array.
- ops
- Raises
- ValueError
If
ops
have different number of rows
Notes
A vertical stack of N linear operators is created such as its application in forward mode leads to
\[\begin{split}\begin{bmatrix} \mathbf{L}_{1} \\ \mathbf{L}_{2} \\ \vdots \\ \mathbf{L}_{N} \end{bmatrix} \mathbf{x} = \begin{bmatrix} \mathbf{L}_{1} \mathbf{x} \\ \mathbf{L}_{2} \mathbf{x} \\ \vdots \\ \mathbf{L}_{N} \mathbf{x} \end{bmatrix} = \begin{bmatrix} \mathbf{y}_{1} \\ \mathbf{y}_{2} \\ \vdots \\ \mathbf{y}_{N} \end{bmatrix}\end{split}\]while its application in adjoint mode leads to
\[\begin{split}\begin{bmatrix} \mathbf{L}_{1}^H & \mathbf{L}_{2}^H & \ldots & \mathbf{L}_{N}^H \end{bmatrix} \begin{bmatrix} \mathbf{y}_{1} \\ \mathbf{y}_{2} \\ \vdots \\ \mathbf{y}_{N} \end{bmatrix} = \mathbf{L}_{1}^H \mathbf{y}_1 + \mathbf{L}_{2}^H \mathbf{y}_2 + \ldots + \mathbf{L}_{N}^H \mathbf{y}_N\end{split}\]- Attributes
Methods
__init__
(ops[, nproc, forceflat, dtype])adjoint
()apply_columns
(cols)Apply subset of columns of operator
cond
([uselobpcg])Condition number of linear operator.
conj
()Complex conjugate operator
div
(y[, niter, densesolver])Solve the linear problem \(\mathbf{y}=\mathbf{A}\mathbf{x}\).
dot
(x)Matrix-matrix or matrix-vector multiplication.
eigs
([neigs, symmetric, niter, uselobpcg])Most significant eigenvalues of linear operator.
matmat
(X)Matrix-matrix multiplication.
matvec
(x)Matrix-vector multiplication.
reset_count
()Reset counters
rmatmat
(X)Matrix-matrix multiplication.
rmatvec
(x)Adjoint matrix-vector multiplication.
todense
([backend])Return dense matrix.
toimag
([forw, adj])Imag operator
toreal
([forw, adj])Real operator
tosparse
()Return sparse matrix.
trace
([neval, method, backend])Trace of linear operator.
transpose
()
Examples using pylops.VStack
#
Operators with Multiprocessing