Function nutm80

pub fn nutm80(date1: f64, date2: f64) -> [[f64; 3]; 3]

Expand description

Form the matrix of nutation for a given date, IAU 1980 model.

This function is part of the International Astronomical Union’s SOFA (Standards of Fundamental Astronomy) software collection.

Status: support function.

Given: date1,date2 double TDB date (Note 1)

Returned (function value): rmatn [[f64; 3]; 3] nutation matrix

Notes:

The TT date date1+date2 is a Julian Date, apportioned in any convenient way between the two arguments. For example, JD(TT)=2450123.7 could be expressed in any of these ways, among others:
```
   date1          date2

2450123.7           0.0       (JD method)
2451545.0       -1421.3       (J2000 method)
2400000.5       50123.2       (MJD method)
2450123.5           0.2       (date & time method)
```
The JD method is the most natural and convenient to use in cases where the loss of several decimal digits of resolution is acceptable. The J2000 method is best matched to the way the argument is handled internally and will deliver the optimum resolution. The MJD method and the date & time methods are both good compromises between resolution and convenience.
The matrix operates in the sense V(true) = rmatn * V(mean), where the p-vector V(true) is with respect to the true equatorial triad of date and the p-vector V(mean) is with respect to the mean equatorial triad of date.

Called: iauNut80 nutation, IAU 1980 iauObl80 mean obliquity, IAU 1980 iauNumat form nutation matrix

nutm80