pycsamt.forward.maxwell.mt2d

Validated adapter for the in-repo 2-D MT finite-difference solver.

MT2DAdapter bridges the solver-neutral MaxwellProblem / ForwardResult contract to the existing, tested finite-difference implementation in pycsamt.forward.em2d (MT2DForward) over a Grid2D model. No new physics is introduced here: this module only translates problem/result shapes and enforces the assumptions the wrapped solver actually makes.

Known solver-specific limits, declared through BackendCapabilities or checked in MT2DAdapter.assess():

• only the zxy (TE) and zyx (TM) impedance components are produced, matching the physical 2-D TE/TM decomposition;

• every receiver must sit exactly at the surface (z = 0); the wrapped solver has no borehole or buried-receiver formulation;

• the earth model has no inactive (air) cells: the solver always treats the full mesh as earth, so a problem must use mark_air_inactive=False when built from to_problem();

• magnetic permeability is fixed at the vacuum value 4*pi*1e-7 H/m, matching pycsamt.forward.em2d.MU0;

• only the exp(+iwt) phasor convention is supported, matching the sign convention hardcoded in pycsamt.forward.em2d.

A numerically degenerate solve (near-zero surface magnetic field at a station) makes pycsamt.forward.em2d fall back to 0 + 0j rather than raise or return NaN; such an entry is currently reported as valid because valid defaults to finiteness. This is a known, narrow limitation inherited from the wrapped solver, not something this adapter can detect from its output alone.

Scipy (a required pycsamt dependency, not optional) is imported only through pycsamt.forward.em2d; this module performs no lazy or optional-dependency handling of its own.

Functions

register_mt2d_backend(*[, replace])

Register MT2DAdapter in the process-wide backend registry.

Classes

MT2DAdapter(*[, version, policy, verbose])

Validated 2-D MT adapter over the in-repo finite-difference solver.

class pycsamt.forward.maxwell.mt2d.MT2DAdapter(*, version='1.0', policy=None, verbose=False)

Bases: BaseMaxwellAdapter

Validated 2-D MT adapter over the in-repo finite-difference solver.

Parameters:

• version (str, default="1.0") – Adapter version reported in every ForwardResult. Bump this when the translation logic in this module changes in a way that could alter numerical output.

• policy (AdapterPolicy or None, optional) – Solver-independent result acceptance policy. Defaults to AdapterPolicy.

• verbose (bool, default=False) – Forwarded to MT2DForward; prints per-frequency progress when true.

Examples

>>> import numpy as np
>>> from pycsamt.forward.maxwell import (
...     MaxwellMesh,
...     MaxwellProblem,
...     ReceiverSet,
... )
>>> mesh = MaxwellMesh(
...     np.linspace(0, 10_000, 41), np.linspace(0, 5_000, 31)
... )
>>> problem = MaxwellProblem(
...     mesh,
...     np.full(mesh.shape, 1.0 / 100.0),
...     [10.0, 1.0],
...     ReceiverSet([[5_000.0, 0.0]], ["S00"]),
...     ("zxy", "zyx"),
... )
>>> adapter = MT2DAdapter(verbose=False)
>>> result = adapter.solve(problem)
>>> result.shape
(1, 2, 2)

assess(problem)

Assess a problem, adding this solver’s surface-only checks.

Parameters:

problem (MaxwellProblem) – Candidate simulation problem.

Returns:

The generic capability report from assess(), extended with two solver-specific checks: every receiver must be at the surface, and the permeability must be the vacuum value the wrapped solver hardcodes.

Return type:

CompatibilityReport

Examples

See MT2DAdapter for a complete solve example; a problem with a buried receiver is rejected before the solver runs.

pycsamt.forward.maxwell.mt2d.register_mt2d_backend(*, replace=False)

Register MT2DAdapter in the process-wide backend registry.

Parameters:

replace (bool, default=False) – Explicitly replace an existing "mt2d" registration.

Return type:

None

Examples

>>> from pycsamt.forward.maxwell import create_backend, list_backends
>>> register_mt2d_backend(replace=True)
>>> "mt2d" in list_backends()
True
>>> create_backend("mt2d").capabilities.name
'mt2d'