SUBROUTINE iau_PN06A ( DATE1, DATE2,
     :                       DPSI, DEPS, EPSA, RB, RP, RBP, RN, RBPN )
*+
*  - - - - - - - - - -
*   i a u _ P N 0 6 A
*  - - - - - - - - - -
*
*  Precession-nutation, IAU 2006/2000A models:  a multi-purpose routine,
*  supporting classical (equinox-based) use directly and CIO-based use
*  indirectly.
*
*  This routine is part of the International Astronomical Union's
*  SOFA (Standards of Fundamental Astronomy) software collection.
*
*  Status:  support routine.
*
*  Given:
*     DATE1,DATE2   d       TT as a 2-part Julian Date (Note 1)
*
*  Returned:
*     DPSI,DEPS     d       nutation (Note 2)
*     EPSA          d       mean obliquity (Note 3)
*     RB          d(3,3)    frame bias matrix (Note 4)
*     RP          d(3,3)    precession matrix (Note 5)
*     RBP         d(3,3)    bias-precession matrix (Note 6)
*     RN          d(3,3)    nutation matrix (Note 7)
*     RBPN        d(3,3)    GCRS-to-true matrix (Notes 8,9)
*
*  Notes:
*
*  1) The TT date DATE1+DATE2 is a Julian Date, apportioned in any
*     convenient way between the two arguments.  For example,
*     JD(TT)=2450123.7 could be expressed in any of these ways,
*     among others:
*
*            DATE1          DATE2
*
*         2450123.7D0        0D0        (JD method)
*          2451545D0      -1421.3D0     (J2000 method)
*         2400000.5D0     50123.2D0     (MJD method)
*         2450123.5D0       0.2D0       (date & time method)
*
*     The JD method is the most natural and convenient to use in
*     cases where the loss of several decimal digits of resolution
*     is acceptable.  The J2000 method is best matched to the way
*     the argument is handled internally and will deliver the
*     optimum resolution.  The MJD method and the date & time methods
*     are both good compromises between resolution and convenience.
*
*  2) The nutation components (luni-solar + planetary, IAU 2000A) in
*     longitude and obliquity are in radians and with respect to the
*     equinox and ecliptic of date.  Free core nutation is omitted;  for
*     the utmost accuracy, use the iau_PN06 routine, where the nutation
*     components are caller-specified.
*
*  3) The mean obliquity is consistent with the IAU 2006 precession.
*
*  4) The matrix RB transforms vectors from GCRS to mean J2000.0 by
*     applying frame bias.
*
*  5) The matrix RP transforms vectors from mean J2000.0 to mean of date
*     by applying precession.
*
*  6) The matrix RBP transforms vectors from GCRS to mean of date by
*     applying frame bias then precession.  It is the product RP x RB.
*
*  7) The matrix RN transforms vectors from mean of date to true of date
*     by applying the nutation (luni-solar + planetary).
*
*  8) The matrix RBPN transforms vectors from GCRS to true of date
*     (CIP/equinox).  It is the product RN x RBP, applying frame bias,
*     precession and nutation in that order.
*
*  9) The X,Y,Z coordinates of the IAU 2006/2000A Celestial Intermediate
*     Pole are elements (3,1-3) of the matrix RBPN.
*
*  Called:
*     iau_NUT06A   nutation, IAU 2006/2000A
*     iau_PN06     bias/precession/nutation results, IAU 2006
*
*  Reference:
*
*     Capitaine, N. & Wallace, P.T., 2006, Astron.Astrophys. 450, 855
*
*  This revision:  2009 December 15
*
*  SOFA release 2020-07-21
*
*  Copyright (C) 2020 IAU SOFA Board.  See notes at end.
*
*-----------------------------------------------------------------------

      IMPLICIT NONE

      DOUBLE PRECISION DATE1, DATE2, DPSI, DEPS, EPSA,
     :                 RB(3,3), RP(3,3), RBP(3,3), RN(3,3), RBPN(3,3)

* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

*  Nutation.
      CALL iau_NUT06A ( DATE1, DATE2, DPSI, DEPS )

*  Remaining results.
      CALL iau_PN06 ( DATE1, DATE2, DPSI, DEPS,
     :                EPSA, RB, RP, RBP, RN, RBPN )

*  Finished.

*+----------------------------------------------------------------------
*
*  Copyright (C) 2020
*  Standards Of Fundamental Astronomy Board
*  of the International Astronomical Union.
*
*  =====================
*  SOFA Software License
*  =====================
*
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*
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*
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*-----------------------------------------------------------------------

      END