Voyager LECP Data Analysis Handbook

Instrument Modeling Reports

An Analysis of the Performance of the Magnetic Deflection System
 in the Voyager Low Energy Charged Particle Experiment

by Sheela Shodhan

E.10 POLY1

****************************************************************************
*                       PROGRAM POLYIN                                     *
* PURPOSE : THIS PROGRAM READS THE COORDINATES OF THE PLANES THAT ARE TO BE*
*          TESTED FROM A FILE AND COMPUTES THE COEFFICIENTS A,B,C,D OF THE *
*          CORRESPONDING PLANE BY CALLING THE ROUTINE 'PLANECOEFF'. THESE  *
*          PLANES FORM THE GEOMETRY OF THE SENSOR SUBSYSTEM.               *
* VARIABLES :                                                              *
* INPUT :                                                                  *
* *.DAT : THE NAME OF THE FILE OF COORDINATES OF THE VERTICES OF THE POLYGO*
*       -NS OF THE MODELLED SENSOR SUBSYSTEM. FOR GAMMA DETECTOR,*=COORGAM1*
*       AND FOR BETA DETECTOR, *=COORBET1.                                 *
* OUTPUT :                                                                 *
* COEFF.DAT : FILE OF THE COEFFICIENTS A,B,C, AND D OF THE PLANES OF THE   *
*            POLYGONS OF THE MODELLED SENSOR SUBSYSTEM.                    *
* OTHERS :                                                                 *
* A, B, C, D : COEFFICIENTS OF THE EQUATION Ax + By + Cz + D = 0 OF THE    *
*             PLANE OF THE POLYGON  OF THE MODELLED SENSOR SUBSYSTEM.      *
* CHAN : 2-D ARRAY WHOSE                                                   *
*       EACH ROW CORRESPONDS TO A PARTICULAR PLANE SURFACE;                *
*       COL. 1:NO. OF VERTICES OF THAT PLANE POLYGON  AND                  *
*       COL. 2>>>COL. NVERT*3+1 :ALL THE COORDINATES OF THE VERTICES OF    *
*                                THAT POLYGON.                             *
* COEFF : 2-D ARRAY WHOSE                                                  *
*       EACH ROW CORRESPONDS TO A PARTICULAR PLANE SURFACE;                *
*       COL. 1>>>COL. 4 :A,B,C,D  COEFFICIENTS OF THE EQUATION OF THE PLANE*
*                       FORMED BY THAT POLYGON.                            *
* NVERT : NUMBER OF VERTICES OF A POLYGON OF THE MODELLED SENSOR SUBSYSTEM.*
* VERT : 2-D ARRAY WHOSE                                                   *
*      EACH ROW CORRESPONDS TO A PARTICULAR VERTEX OF A POLYGON;           *
*      COL. 1>>>COL.3 : COORDINATES (X,Y,Z) OF A VERTEX OF A POLYGON.      *
****************************************************************************

      PROGRAM POLYIN
      IMPLICIT NONE
      CHARACTER*72 FNAME
      INTEGER I,I1,I2,J,K,MAXCOO,MAXSURF,NCOL,NERR,NVERT,NTY
      PARAMETER (MAXCOO=95,MAXSURF=50)
      REAL*8 A,B,C,CHAN(MAXSURF,MAXCOO),COEFF(MAXSURF,4),D,VERT(35,3)
      INTEGER NV(MAXSURF)

      OPEN (UNIT=2,STATUS='NEW',FILE='COEFF.DAT')
      WRITE(6,*) 'ENTER THE NAME OF THE FILE OF COORDINATES'
      READ(5,10) FNAME
      OPEN (UNIT=1,STATUS='OLD',FILE=FNAME)  
      READ (1,*)
2     READ(1,*,END=70) NTY
      READ(1,*) NVERT
      CHAN(NTY,1) = DFLOAT(NVERT)
      I1=2
3     READ(1,20,ERR=2) (CHAN(NTY,K),K=I1,I1+2)
      I1=K
      GO TO 3
70    CLOSE(1)

C  TO INITIALISE THE ARRAY WITH THE COORDINATES TO FIND THE COEFFICIENTS

      DO I=1,NTY
       I1 = 2 
       NVERT = IDINT(CHAN(I,1))
       NCOL = NVERT*3 + 1
       J = 1
       DO I2=1,NVERT
        DO WHILE ((J .LE. 3) .AND. (I1 .LE. NCOL))
         VERT(I2,J) = CHAN(I,I1)
         J = J+1
         I1 = I1+1
        END DO
        J = 1
       END DO

       CALL PLANECOEFF(VERT,NVERT,A,B,C,D,NERR)
C  TO INITIALISE THE ARRAY COEFF WITH THE COEFFICIENTS OF THE PLANE
       COEFF(I,1) = A
       COEFF(I,2) = B
       COEFF(I,3) = C
       COEFF(I,4) = D

       WRITE(2,30) I,NVERT,(COEFF(I,J),J=1,4)
       DO J=1,3
        VERT(I,J) = 0.0D0
       END DO
      END DO
  

 10   FORMAT(A72)
 20   FORMAT(3(X,F9.6))
 30   FORMAT(1X,I3,1X,I3,4(1X,D13.6))
      STOP
      END

C---------------------------------------------------------------------------
C---------------------------------------------------------------------------

      SUBROUTINE PLANECOEFF(VE,NVERT,A,B,C,D,NERR)

* PURPOSE : THIS ROUTINE DETERMINES THE COEFFICIENTS A, B, C, AND D OF THE *
*          EQUATION Ax + By + Cz + D = 0 OF THE PLANE OF THE POLYGON OF THE*
*          MODELLED SENSOR SUBSYSTEM. IT SOLVES THE COFACTORS OF A DETERMIN*
*         -ANT FORMED BY THE FIRST THREE VERTICES OF THE POLYGON TO FIND A,*
*          B, C AND D. THEN, IT CHECKS WHETHER THE REST OF THE VERTICES OF *
*          THE POLYGON SATISFIES THIS EQUATION OF THE PLANE WITHIN A CERTAI*
*         -N TOLERANCE OR NOT.                                             * 
* VARIABLES :                                                              *
* INPUT :                                                                  *
* NVERT : NUMBER OF VERTICES OF THE POLYGON.                               *
* VE : 2-D ARRAY WHOSE                                                     *
*      EACH ROW CORRESPONDS TO A PARTICULAR VERTEX OF A POLYGON;           *
*      COL. 1>>>COL.3 : COORDINATES (X,Y,Z) OF A VERTEX OF A POLYGON.      *
* OUTPUT :                                                                 *
* A, B, C, D : COEFFICIENTS OF THE EQUATION Ax + By + Cz + D = 0 OF THE    *
*             PLANE OF THE POLYGON.                                        *
* OTHERS :                                                                 *
* NERR : ERROR INDICATOR                                                   *
*       =1 INDICATES THAT ONE OF THE VERTICES OF THE POLYGON DOES NOT SATIS*
*          -FY THE EQUATION OF THE PLANE WITHIN THE SPECIFIED TOLERANCE.   *
*       =0 NO ERROR.                                                       *
* TOL : TOLERANCE TO WITHIN WHICH ALL THE OTHER VERTICES SATISFY THE EQUATI*
*      -ON OF THE PLANE.                                                   *
****************************************************************************

      IMPLICIT NONE
      INTEGER I,I2,J,NERR,NVERT
      REAL*8 A,B,C,D,DIF,TOL,VE(35,3)
      DATA TOL/1.0D-05/
      

      A=0.D0
      B=0.D0
      C=0.D0
      D=0.D0

C     SOLVE THE COFACTORS OF A DETERMINANT TO GET A,B,C,D

      DO I=1,3
         IF (I.NE.3) THEN
            J=I+1
         ELSE
            J=1
         END IF
         A=A+(VE(I,2)*VE(J,3)-VE(I,3)*VE(J,2))
         B=B+(VE(I,3)*VE(J,1)-VE(I,1)*VE(J,3))
         C=C+(VE(I,1)*VE(J,2)-VE(I,2)*VE(J,1))
      END DO

      D=VE(1,1)*(VE(2,3)*VE(3,2)-VE(3,3)*VE(2,2))
      D=D+VE(1,2)*(VE(2,1)*VE(3,3)-VE(3,1)*VE(2,3))
      D=D+VE(1,3)*(VE(2,2)*VE(3,1)-VE(2,1)*VE(3,2))

C     TEST IF THE REST OF THE VERTICES LIE IN THE PLANE
C
      I=4
      DO WHILE (I.LE.NVERT.AND.DIF.LE.TOL)
         DIF=DABS(A*VE(I,1)+B*VE(I,2)+C*VE(I,3)+D)
D        WRITE(6,*) ' I: ',I,' DIF: ',DIF
         I=I+1
      END DO

      IF (DIF.LE.TOL) THEN
         NERR=0
      ELSE
         NERR=1
         PRINT *,'ERROR IN THE COEFFICIENTS OF PLANE:',I
      END IF

      RETURN
      END
C---------------------------------------------------------------------------
C---------------------------------------------------------------------------

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