### SLA_PRECL

Precession Matrix (latest)

ACTION:
Form the matrix of precession between two epochs, using the model of Simon et al. (1994), which is suitable for long periods of time.
CALL:
CALL sla_PRECL (EP0, EP1, RMATP)
##### GIVEN:
 EP0 D beginning epoch EP1 D ending epoch

##### RETURNED:
 RMATP D(3,3) precession matrix

NOTES:
(1)
The epochs are TDB Julian epochs.
(2)
The matrix is in the sense:

v${}_{1}$ = M$\cdot$v${}_{0}$

where v${}_{1}$ is the star vector relative to the mean equator and equinox of epoch EP1, M is the $3×3$ matrix RMATP and v${}_{0}$ is the star vector relative to the mean equator and equinox of epoch EP0.
(3)
The absolute accuracy of the model is limited by the uncertainty in the general precession, about ′′03 per 1000 years. The remainder of the formulation provides a precision of 1 milliarcsecond over the interval from 1000 AD to 3000 AD, ′′01 from 1000 BC to 5000 AD and $1\phantom{\rule{-0.54753pt}{0ex}}$${}^{\prime }{\phantom{\rule{-1.09506pt}{0ex}}}^{\prime }$ from 4000 BC to 8000 AD.
REFERENCE:
Simon, J.L. et al., 1994. Astr.Astrophys. 282, 663.