meepmeep.numba3d.zvel_cd

meepmeep.numba3d.zvel_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 velocity and its parameter derivatives at an expansion-point-centered time.

Centered companion to velocity.zvel_c that additionally returns the partial derivatives of the line-of-sight velocity 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 velocity.zvel_c.

Parameters:

timefloat or ndarray

Time(s) 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.

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:

vzfloat or ndarray

Line-of-sight z velocity in stellar radii per unit time. Positive values indicate motion toward the observer. Shape (N,) for an array time.

dvzNDArray

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