fw2m¶
-
erfa.
fw2m
(gamb, phib, psi, eps)[source]¶ Wrapper for ERFA function
eraFw2m
.- Parameters
- gambdouble array
- phibdouble array
- psidouble array
- epsdouble array
- Returns
- rdouble array
Notes
The ERFA documentation is below.
- - - - - - - - e r a F w 2 m - - - - - - - - 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.