mirror of
https://github.com/eddyem/apogee_control.git
synced 2025-12-06 10:45:20 +03:00
85 lines
2.2 KiB
Fortran
85 lines
2.2 KiB
Fortran
SUBROUTINE sla_AV2M (AXVEC, RMAT)
|
|
*+
|
|
* - - - - -
|
|
* A V 2 M
|
|
* - - - - -
|
|
*
|
|
* Form the rotation matrix corresponding to a given axial vector.
|
|
*
|
|
* (single precision)
|
|
*
|
|
* A rotation matrix describes a rotation about some arbitrary axis,
|
|
* called the Euler axis. The "axial vector" supplied to this routine
|
|
* has the same direction as the Euler axis, and its magnitude is the
|
|
* amount of rotation in radians.
|
|
*
|
|
* Given:
|
|
* AXVEC r(3) axial vector (radians)
|
|
*
|
|
* Returned:
|
|
* RMAT r(3,3) rotation matrix
|
|
*
|
|
* If AXVEC is null, the unit matrix is returned.
|
|
*
|
|
* The reference frame rotates clockwise as seen looking along
|
|
* the axial vector from the origin.
|
|
*
|
|
* Last revision: 26 November 2005
|
|
*
|
|
* Copyright P.T.Wallace. All rights reserved.
|
|
*
|
|
* License:
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program (see SLA_CONDITIONS); if not, write to the
|
|
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
|
|
* Boston, MA 02111-1307 USA
|
|
*
|
|
*-
|
|
|
|
IMPLICIT NONE
|
|
|
|
REAL AXVEC(3),RMAT(3,3)
|
|
|
|
REAL X,Y,Z,PHI,S,C,W
|
|
|
|
|
|
|
|
* Rotation angle - magnitude of axial vector - and functions
|
|
X = AXVEC(1)
|
|
Y = AXVEC(2)
|
|
Z = AXVEC(3)
|
|
PHI = SQRT(X*X+Y*Y+Z*Z)
|
|
S = SIN(PHI)
|
|
C = COS(PHI)
|
|
W = 1.0-C
|
|
|
|
* Euler axis - direction of axial vector (perhaps null)
|
|
IF (PHI.NE.0.0) THEN
|
|
X = X/PHI
|
|
Y = Y/PHI
|
|
Z = Z/PHI
|
|
END IF
|
|
|
|
* Compute the rotation matrix
|
|
RMAT(1,1) = X*X*W+C
|
|
RMAT(1,2) = X*Y*W+Z*S
|
|
RMAT(1,3) = X*Z*W-Y*S
|
|
RMAT(2,1) = X*Y*W-Z*S
|
|
RMAT(2,2) = Y*Y*W+C
|
|
RMAT(2,3) = Y*Z*W+X*S
|
|
RMAT(3,1) = X*Z*W+Y*S
|
|
RMAT(3,2) = Y*Z*W-X*S
|
|
RMAT(3,3) = Z*Z*W+C
|
|
|
|
END
|