wave_grating_orders — MATH wave op

• Data kinds: none → table (an op determined by its arguments alone — it takes no image or data input)

• Call: import fullseye as fs; fs.ledger.wave_grating_orders(pitch_um=1.6, wavelength_nm=550.0, sin_in=0.0, orders=(-2, -1, 1, 2)) (to call the implementation directly, import mathops; mathops.wave_grating_orders(pitch_um=1.6, wavelength_nm=550.0, sin_in=0.0, orders=(-2, -1, 1, 2)); from the registry, opsmath.get("wave_grating_orders"))

Usage

Where a grating sends each order: `d (sin_out - sin_in) = m lambda` solved for the angle.

The companion to the existing `grating_wavelengths` (which solves the same

identity for *lambda*): given the pitch and the wavelength, this returns the

outgoing direction of each order, and marks the orders that are

evanescent — `|sin_out| > 1` means that order does not propagate, which

is why a CD shows fewer colours at grazing incidence.

★Why this earns its place: the two ops invert one another, so a round trip

must return the wavelength it started from; and the angles can be compared

against the peak positions of a *simulated* far field (the existing

`fraunhofer_pattern` of a real grating aperture), which knows nothing about

the grating equation.

Returns a `table: order, sin_out, angle_deg` (NaN when

evanescent), `propagates`.

Raises `ValueError: non-positive pitch or wavelength; |sin_in| > 1`;

order 0 alone with no others (it is always the specular direction — allowed,

but a caller asking only for it probably meant something else); non-finite input.

Family-wide input contract (fail-closed)

Every mathops op validates its input before computing (nothing slips through silently):

• **complex input raises ValueError** — coercing to float64 silently discards the imaginary part (numpy only emits a ComplexWarning and returns a plausible-looking wrong real number). State .real/.imag/abs() explicitly, or use complexops, which handles complex data.

• **masked arrays with masked elements raise ValueError** — the implicit conversion that peels off the mask and uses the raw values underneath is refused. Say explicitly whether to fill or to drop.

• **NaN/Inf raises ValueError on every input** (refused with the count stated — it propagates through the whole result).

• Shapes are strict: 1-D and 2-D are never implicitly promoted or broadcast (a matrix in a vector slot, or a vector in a matrix slot, raises ValueError; reshape explicitly).

• Size cap: ops that take a matrix, and the stat_histogram bins, raise ValueError beyond mathops.MAX_ELEMENTS (2^26 ≈ 67 million elements).

Detailed usage guide

• math_metrology family guide

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• poc_beats_fringes_and_screens — py -3.11 examples/poc_beats_fringes_and_screens.py

Ops the type connects to (they accept table as input)

dynsys_poincare_section

Same category (wave)

wave_membrane_mode · wave_mode_frequencies · wave_nodal_lines · wave_two_slit · wave_fringe_period


*Provenance: mathops.py — MATH operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.