meepmeep.numba3d.cos_alpha_d

meepmeep.numba3d.cos_alpha_d(time: float | ndarray[tuple[Any, ...], dtype[_ScalarT]], tc: float, p: float, c: ndarray[tuple[Any, ...], dtype[_ScalarT]], dc: ndarray[tuple[Any, ...], dtype[_ScalarT]], te: float = 0.0)

Evaluate the cosine of the orbital phase angle and its parameter derivatives at an absolute time.

Direct counterpart of cos_alpha_cd: epoch-folds the absolute time time around the expansion point and delegates to cos_alpha_cd.

Accepts a scalar time or a 1-D array of times and dispatches to the appropriate kernel at compile time (inside @njit) or at call time (pure Python), mirroring the value-only cos_phase_angle.cos_alpha.

Parameters:

timefloat or ndarray

Absolute observation time(s) in the same units as tc and p.

tcfloat

Transit-centre time (time of inferior conjunction), on the same time axis as time.

pfloat

Orbital period, used for epoch folding.

cNDArray

A (3, 5) Taylor coefficient matrix produced by solve3d.

dcNDArray

A (7, 3, 5) parameter-derivative tensor produced by solve3d_d, with the leading axis ordered as (tc, p, a, i, e, w, lan).

tefloat, optional

Expansion-point offset from the transit centre [days] - the same value that was passed to solve3d_d. Defaults to 0.0, the expansion point at the transit centre.

Returns:

cafloat or ndarray

Cosine of the phase angle, in [-1, 1]. Shape (N,) for an array time.

dcaNDArray

Partial derivatives of ca with respect to (tc, p, a, i, e, w, lan). Shape (7,) for a scalar time, (N, 7) for an array time.