#include "slalib.h" #include "slamac.h" void slaPrenut ( double epoch, double date, double rmatpn[3][3] ) /* ** - - - - - - - - - - ** s l a P r e n u t ** - - - - - - - - - - ** ** Form the matrix of precession and nutation (IAU 1976 / FK5) ** ** (double precision) ** ** Given: ** epoch double Julian epoch for mean coordinates ** date double Modified Julian Date (JD-2400000.5) ** for true coordinates ** ** ** Returned: ** rmatpn double[3][3] combined precession/nutation matrix ** ** Called: slaPrec, slaEpj, slaNut, slaDmxm ** ** Notes: ** ** 1) The epoch and date are TDB (loosely ET). ** ** 2) The matrix is in the sense v(true) = rmatpn * v(mean) . ** ** Last revision: 15 July 1993 ** ** Copyright P.T.Wallace. All rights reserved. */ { double rmatp[3][3], rmatn[3][3]; /* Precession */ slaPrec ( epoch, slaEpj ( date ), rmatp ); /* Nutation */ slaNut ( date, rmatn ); /* Combine the matrices: pn = n x p */ slaDmxm ( rmatn, rmatp, rmatpn ); }