Convert cylindrical radius and polar angle to Cartesian z‑coordinate

Handles regular points as well as the two pole regions (θ≈0 and θ≈π). Non‑finite inputs remain NA.

Usage

spherical_to_z(rho, theta)

Arguments

rho

Numeric vector – cylindrical radius (√(x² + y²)).

theta

Numeric vector – polar angle measured from the +z axis (radians).

Value

Numeric vector of z‑coordinates (same length as input)