meepmeep.numba3d.zpos_cd

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

Evaluate the line-of-sight z position and its parameter derivatives at an expansion-point-centered time.

Centered companion to position.zpos_c that additionally returns the partial derivatives of the line-of-sight coordinate with respect to each of the seven orbital parameters. Only the z-direction polynomials are evaluated; the x and y rows of c and dc are not read.

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 position.zpos_c.

Parameters:

timefloat or ndarray

Time(s) relative to the Taylor series expansion point.

cNDArray

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

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). Only the slice dc[:, 2, :] is read.

Returns:

pzfloat or ndarray

Line-of-sight z position in units of stellar radii. Positive values point toward the observer. Shape (N,) for an array time.

dpzNDArray

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