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SUBROUTINE slVN (V, UV, VM)
*+
* - - -
* V N
* - - -
*
* Normalizes a 3-vector also giving the modulus (single precision)
*
* Given:
* V real(3) vector
*
* Returned:
* UV real(3) unit vector in direction of V
* VM real modulus of V
*
* If the modulus of V is zero, UV is set to zero as well
*
* P.T.Wallace Starlink 23 November 1995
*
* Copyright (C) 1995 Rutherford Appleton Laboratory
*
* 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., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301 USA
*
* Copyright (C) 1995 Association of Universities for Research in Astronomy Inc.
*-
IMPLICIT NONE
REAL V(3),UV(3),VM
INTEGER I
REAL W1,W2
* Modulus
W1=0.0
DO I=1,3
W2=V(I)
W1=W1+W2*W2
END DO
W1=SQRT(W1)
VM=W1
* Normalize the vector
IF (W1.LE.0.0) W1=1.0
DO I=1,3
UV(I)=V(I)/W1
END DO
END
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