fw2m

erfa.fw2m(gamb, phib, psi, eps)[source]

Wrapper for ERFA function eraFw2m.

Parameters

gamb : double array

phib : double array

psi : double array

eps : double array

Returns

r : double array

Notes

The ERFA documentation is below.

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 e r a F w 2 m
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Form rotation matrix given the Fukushima-Williams angles.

Given:
   gamb     double         F-W angle gamma_bar (radians)
   phib     double         F-W angle phi_bar (radians)
   psi      double         F-W angle psi (radians)
   eps      double         F-W angle epsilon (radians)

Returned:
   r        double[3][3]   rotation matrix

Notes:

1) Naming the following points:

         e = J2000.0 ecliptic pole,
         p = GCRS pole,
         E = ecliptic pole of date,
   and   P = CIP,

   the four Fukushima-Williams angles are as follows:

      gamb = gamma = epE
      phib = phi = pE
      psi = psi = pEP
      eps = epsilon = EP

2) The matrix representing the combined effects of frame bias,
   precession and nutation is:

      NxPxB = R_1(-eps).R_3(-psi).R_1(phib).R_3(gamb)

3) Three different matrices can be constructed, depending on the
   supplied angles:

   o  To obtain the nutation x precession x frame bias matrix,
      generate the four precession angles, generate the nutation
      components and add them to the psi_bar and epsilon_A angles,
      and call the present function.

   o  To obtain the precession x frame bias matrix, generate the
      four precession angles and call the present function.

   o  To obtain the frame bias matrix, generate the four precession
      angles for date J2000.0 and call the present function.

   The nutation-only and precession-only matrices can if necessary
   be obtained by combining these three appropriately.

Called:
   eraIr        initialize r-matrix to identity
   eraRz        rotate around Z-axis
   eraRx        rotate around X-axis

Reference:

   Hilton, J. et al., 2006, Celest.Mech.Dyn.Astron. 94, 351

Copyright (C) 2013-2019, NumFOCUS Foundation.
Derived, with permission, from the SOFA library.  See notes at end of file.