GEANT321/gphys/gvrot.F

   1 *
   2 * $Id$
   3 *
   4 * $Log$
   5 * Revision 1.1.1.1  1995/10/24 10:21:35  cernlib
   6 * Geant
   7 *
   8 *
   9 #include "geant321/pilot.h"
  10 *CMZ :  3.21/02 29/03/94  15.41.23  by  S.Giani
  11 *-- Author :
  12       SUBROUTINE GVROT(DCOSIN,PART)
  13 C.
  14 C.    ******************************************************************
  15 C.    *                                                                *
  16 C.    *  Rotates vector from one reference system into another         *
  17 C.    *  defined by the direction cosines contained in the vector      *
  18 C.    *  DCOSIN. The input vector PART is overwritten.                 *
  19 C.    *                                                                *
  20 C.    *    ==>Called by :                                              *
  21 C.    *       Author    F.Carminati **********                         *
  22 C.    *                                                                *
  23 C.    *                                                                *
  24 C.    ******************************************************************
  25 C.
  26       DIMENSION PART(*),DCOSIN(*)
  27 #if !defined(CERNLIB_SINGLE)
  28       DOUBLE PRECISION DUX,DUY,DUZ,SINTH2,ONE,COSTH,SINTH,COSPH,SINPH
  29       DOUBLE PRECISION DNORM
  30 #endif
  31       LOGICAL ROTATE
  32       PARAMETER (ONE=1)
  33 C.
  34 C.    ------------------------------------------------------------------
  35 C.
  36       DUX      = DCOSIN(1)
  37       DUY      = DCOSIN(2)
  38       DUZ      = DCOSIN(3)
  39       ROTATE   = .TRUE.
  40       IF(ABS(DUZ).GE.0.85) THEN
  41          SINTH2=DUX**2+DUY**2
  42          IF(SINTH2.GT.0.) THEN
  43             COSTH  = SIGN(ONE,DUZ)*SQRT(ONE-SINTH2)
  44             SINTH  = SQRT(SINTH2)
  45             COSPH  = DUX/SINTH
  46             SINPH  = DUY/SINTH
  47          ELSEIF(DUZ.GT.0.)THEN
  48             ROTATE = .FALSE.
  49          ELSE
  50             COSTH = -1.
  51             SINTH =  0.
  52             COSPH =  1.
  53             SINPH =  0.
  54          ENDIF
  55       ELSE
  56          COSTH  = DUZ
  57          SINTH  = SQRT((ONE+DUZ)*(ONE-DUZ))
  58          DNORM  = ONE/SQRT(DUX**2+DUY**2)
  59          COSPH  = DUX*DNORM
  60          SINPH  = DUY*DNORM
  61       ENDIF
  62 *
  63       IF(ROTATE) THEN
  64          P1=PART(1)
  65          P2=PART(2)
  66          P3=PART(3)
  67          PART(1)= P1*COSTH*COSPH - P2*SINPH + P3*SINTH*COSPH
  68          PART(2)= P1*COSTH*SINPH + P2*COSPH + P3*SINTH*SINPH
  69          PART(3)=-P1*SINTH                  + P3*COSTH
  70       ENDIF
  71 C
  72       END