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numat

sofars::pnp

Function numat 

Source 
pub fn numat(epsa: f64, dpsi: f64, deps: f64, rmatn: &mut [[f64; 3]; 3])
Expand description

Form the matrix of nutation.

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

Status: support function.

Given: epsa double mean obliquity of date (Note 1) dpsi,deps double nutation (Note 2)

Returned: rmatn double[3][3] nutation matrix (Note 3)

Notes:

  1. The supplied mean obliquity epsa, must be consistent with the precession-nutation models from which dpsi and deps were obtained.

  2. The caller is responsible for providing the nutation components; they are in longitude and obliquity, in radians and are with respect to the equinox and ecliptic of date.

  3. 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: iauIr initialize r-matrix to identity iauRx rotate around X-axis iauRz rotate around Z-axis

Reference:

Explanatory Supplement to the Astronomical Almanac, P. Kenneth Seidelmann (ed), University Science Books (1992), Section 3.222-3 (p114).

This revision: 2021 May 11

SOFA release 2023-10-11

Copyright (C) 2023 IAU SOFA Board. See notes at end.