SLA_PRENUT - Precession/Nutation Matrix   

ACTION:

Form the matrix of precession and nutation (IAU 1976, FK5).

CALL:

CALL sla_PRENUT (EPOCH, DATE, RMATPN)

GIVEN:

EPOCH Julian Epoch for mean coordinates

DATE D Modified Julian Date (JD-2400000.5) for true coordinates

RETURNED:

RMATPN combined precession/nutation matrix

NOTES:

1.

The epoch and date are TDB.

2.

The matrix is in the sense:

v_true = M$\cdot$v_mean

where v_true is the star vector relative to the true equator and equinox of epoch DATE, M is the $3\times3$ matrix RMATPN and v_mean is the star vector relative to the mean equator and equinox of epoch EPOCH.