pub fn decimal_year(year: i32, month: u32, day: u32) -> Result<f64, CoreError>Expand description
A calendar date as a decimal year: year + (d − 1) / L, where d is the day of the year
(1 for January 1) and L is 365 or 366. This is the start of the day. Outside the blackout
zones around the magnetic poles (CompassZone), the declination changes within a day by a
few thousandths of a degree at most, far below the model’s own error.
§Errors
CoreError::Domain if month is not 1 to 12 or day is not a day of that month
(Gregorian calendar).