The IAU 2006 precession matrix from ep0 to ep1 is found and returned. The matrix is in the sense V(EP1) = RMATP $\ast$ V(EP0). The epochs are TDB (loosely TT) Julian epochs.

Though the matrix method itself is rigorous, the precession angles are expressed through canonical polynomials which are valid only for a limited time span of a few hundred years around the current epoch.

palPrec( double ep0, double ep1, double rmatp[3][3] )

ep0 = double (Given)

ep1 = double (Given)

rmatp = double[3][3] (Returned)