meepmeep.numba3d.zpos_c

meepmeep.numba3d.zpos_c(time: float | ndarray[tuple[Any, ...], dtype[_ScalarT]], c: ndarray[tuple[Any, ...], dtype[_ScalarT]]) → float | ndarray[tuple[Any, ...], dtype[_ScalarT]]

Evaluate the planet’s line-of-sight z position at an expansion-point-centered time.

Centered counterpart of zpos: evaluates only the z-direction Taylor polynomial (row 2 of c), skipping the x and y rows. This is the cheapest 3D evaluator in the module and is the right choice when only the transit/eclipse branch is needed (e.g. to discriminate primary from secondary eclipse via the sign of z).

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).

Parameters:

timefloat or NDArray

Time relative to the Taylor series expansion point.

cNDArray

A (3, 5) coefficient matrix produced by solve3d. Only row 2 (the z-direction coefficients) is read.

Returns:

pzfloat or NDArray

Line-of-sight z position in units of stellar radii. Positive values point toward the observer; negative values point away.