fw2m¶
- erfa.fw2m(gamb, phib, psi, eps)[source]¶
Form rotation matrix given the Fukushima-Williams angles.
- Parameters:
- gambdouble array
- phibdouble array
- psidouble array
- epsdouble array
- Returns:
- rdouble array
Notes
Wraps ERFA function
eraFw2m
. The ERFA documentation is:- - - - - - - - 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) The present function can construct three different matrices, depending on which angles are supplied as the arguments gamb, phib, psi and eps: o To obtain the nutation x precession x frame bias matrix, first generate the four precession angles known conventionally as gamma_bar, phi_bar, psi_bar and epsilon_A, then generate the nutation components Dpsi and Depsilon and add them to psi_bar and epsilon_A, and finally call the present function using those four angles as arguments. 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 References: Capitaine, N. & Wallace, P.T., 2006, Astron.Astrophys. 450, 855 Hilton, J. et al., 2006, Celest.Mech.Dyn.Astron. 94, 351 This revision: 2021 May 11 Copyright (C) 2013-2023, NumFOCUS Foundation. Derived, with permission, from the SOFA library. See notes at end of file.