pylops.Zero

class pylops.Zero(N, M=None, forceflat=None, dtype='float64', name='Z')

Zero operator.

Transform model into array of zeros of size \(N\) in forward and transform data into array of zeros of size \(N\) in adjoint.

Parameters:

Nint or tuple

Number of samples in data (and model, if M is not provided). If a tuple is provided, this is interpreted as the data (and model) are nd-arrays.

Mint or tuple, optional

Number of samples in model. If a tuple is provided, this is interpreted as the model is an nd-array. Note that when M is a tuple, N must be also a tuple with the same number of elements.

forceflatbool, optional

Added in version 2.2.0.

Force an array to be flattened after matvec and rmatvec. Note that this is only required when N and M are tuples (input and output arrays are nd-arrays).

dtypestr, optional

Type of elements in input array.

namestr, optional

Added in version 2.0.0.

Name of operator (to be used by pylops.utils.describe.describe)

Attributes:

dimstuple

Shape of the array after the adjoint, but before flattening.

For example, x_reshaped = (Op.H * y.ravel()).reshape(Op.dims).

dimsdtuple

Shape of the array after the forward, but before flattening.

For example, y_reshaped = (Op * x.ravel()).reshape(Op.dimsd).

shapetuple

Operator shape.

Notes

An Zero operator simply creates a null data vector \(\mathbf{y}\) in forward mode:

\[\mathbf{0} \mathbf{x} = \mathbf{0}_N\]

and a null model vector \(\mathbf{x}\) in forward mode:

\[\mathbf{0} \mathbf{y} = \mathbf{0}_M\]

Methods

__init__(N[, M, forceflat, dtype, name])
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.Zero

Operators concatenation

Operators concatenation

Zero

Zero