Function singleaxis 

pub fn singleaxis(
    solar_zenith: f64,
    solar_azimuth: f64,
    axis_tilt: f64,
    axis_azimuth: f64,
    max_angle: f64,
    backtrack: bool,
    gcr: f64,
) -> (f64, f64, f64)

Calculate single-axis tracker positions with backtracking support.

Arguments

• solar_zenith - Apparent solar zenith angle in degrees.
• solar_azimuth - Apparent solar azimuth angle in degrees.
• axis_tilt - Tilt of the tracker axis from horizontal in degrees.
• axis_azimuth - Azimuth of the tracker axis in degrees (North=0, East=90).
• max_angle - Maximum rotation angle of the tracker from horizontal (e.g. 45.0 or 60.0 degrees).
• backtrack - Enable backtracking (True).
• gcr - Ground Coverage Ratio (module width / row pitch).

Returns

A tuple containing (surface_tilt, surface_azimuth, aoi). All in degrees.