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.17 DMAIN1

*****************************************************************************
*                       PROGRAM DMAIN1                                      *
* PURPOSE : THIS IS THE MAIN PROGRAM IN A SET OF ROUTINES TO CALCULATE THE  *
*          MAGNETIC FIELD AT DESIRED POINTS IN SPACE AND TO PLOT THE FIELD  *
*          VALUES WITH RESPECT TO X OR Y AXIS.                              *
* ROUTINES TO BE LINKED : DMAIN1, DMAINTESTIN1, FDMOD1, PLOTR4MYY1          *
* DESCRIPTION : (1) DMAIN1:THIS IS THE MAIN ROUTINE TO FIND THE FIELD VALUES*
*                 AT THE DESIRED POINTS IN SPACE. IT READS IN THE EXPERIMENT*
*                -ALLY OBSERVED VALUES FROM THE DATA FILE 'BFIELD.DAT', ITER*
*                -ATES UPON THE COORDINATES X AND Y AT Z=0.0, FINDS THE     *
*                 MAGNETIC FIELD AND COMPUTES THE RELATIVE PERCENTAGE ERROR *
*                 BETWEEN THE EXPERIMENTALLY OBSERVED VALUES AND THE CALCULA*
*                -TED VALUES AT THOSE DESIRED POINTS. FINALLY, IT HANDS     *
*                 IN THE ARRAYS THAT CONTAIN THE EXPERIMENTALLY OBSERVED VAL*
*                -UES (EXPT) AND THE CALCULATED VALUES (MGZ) TO THE ROUTINE *
*                 DMAINTESTIN1 SO THAT THESE CAN BE PLOTTED.                *
*                 THE MAIN PURPOSE IS THAT VARIOUS MODELS OF THE MAGNETIC   *
*                 FIELD CAN BE TESTED BY THIS SET OF ROUTINES SINCE IT HAS  *
*                 TO BE LINKED WITH FDMOD1 WHICH COMPUTES THE FIELD IN SPACE*
*                 AND WHICH IS CHANGEABLE.                                  *
* FOR A MORE DETAILED EXPLANATION, PLEASE SEE THE COMMENTS IN THE ROUTINES  *
* THEMSELVES.                                                               *
*               (2) DMAINTESTIN1:THIS ROUTINE READS FROM THE ARRAYS OF EXPER*
*               -IMENTALLY OBSERVED VALUES AND CALCULATED VALUES INTO ARRAYS*
*                WHICH CAN THEN BE SENT TO THE PLOT ROUTINE SO THAT THESE VA*
*               -LUES CAN BE PLOTTED.                                       *
*               (3) FDMOD1:THIS IS THE ROUTINE THAT COMPUTES THE FIELD COMPO*
*               -NENTS Bx, By AND Bz AT A GIVEN POINT (X,Y,Z) IN SPACE.     *
*               (4) PLOTR4MYY1:THIS PLOTS THE EXPERIMENTALLY OBSERVED VALUES*
*                AND THE CALCULATED VALUES WITH RESPECT TO THE X AND THE Y  *
*                COORDINATES.                                               *
* VARIABLES :                                                               *
* BX, BY, BZ, B : X,Y,Z AND THE TOTAL FIELD VALUES RESPECTIVELY AT A POINT  *
*                IN SPACE.                                                  *
* NOTE : THE FOLLOWING ARRAYS ARE ALL DOUBLE PRECISION ARRAYS.              *
* DIFF : 2-D ARRAY THAT CONTAINS THE RELATIVE PERCENTAGE ERROR BETWEEN THE  *
*       EXPERIMENTALLY OBSERVED VALUES AND THE CALCULATED VALUES.           *
* EXPT : 2-D ARRAY THAT CONTAINS THE EXPERIMENTALLY OBSERVED VALUES AT THE  *
*       GIVEN POINTS IN SPACE. Z=0.0, X=-0.9 >> 0.8 AND Y=-1.1>>0.5. NOTE:  *
*       ALL THE MEASUREMENTS ARE IN INCHES.                                 *
* MAGB : 2-D ARRAY THAT CONTAINS THE CALCULATED TOTAL FIELD VALUES AT THE   *
*       REQUIRED POINTS IN SPACE.                                           *
* MGX, MGY, MGZ : 2-D ARRAYS THAT CONTAIN THE X, Y AND Z COMPONENT RESPECTIV*
*                -ELY OF THE MAGNETIC FIELD AT THE REQUIRED POINTS IN SPACE.*
* NOTE : THE FOLLOWING ARRAYS ARE ALL SINGLE PRECISION ARRAYS.              *
* DIFF1, EXPT1, MGZ1 : CORRESPONDING SINGLE PRECISION ARRAYS FOR DIFF, EXPT *
*                     AND MGZ.                                              *
*****************************************************************************
     

        IMPLICIT NONE        
        INTEGER NX,NY
        REAL*8 X,Y,Z
	REAL*8 BX,BY,BZ,B
        REAL*8 MAGB(-9:8,-11:5),NORMB(-9:8,-11:5),EXPT(-9:8,-11:5)
        REAL*8 MGX(-9:8,-11:5),MGY(-9:8,-11:5),MGZ(-9:8,-11:5)
        REAL*8 DIFF(-9:8,-11:5)
        REAL DIFF1(-9:8,-11:5),MGZ1(-9:8,-11:5),EXPT1(-9:8,-11:5)

        PRINT *,'PLEASE WAIT!'

        OPEN(1,FILE='EXTTES.DAT',ACCESS='SEQUENTIAL',STATUS='NEW')
        OPEN(2,FILE='BFIELD.DAT',ACCESS='SEQUENTIAL',STATUS='OLD')

        DO NY = 5,-11,-1
          DO NX = 8,-9,-1
             READ(2,*) EXPT(NX,NY)   
          END DO
        END DO

        Z = 0.0d0

  	DO NY = -11,5
          DO NX = -9,8

             X = DFLOAT(NX) * 0.1d0
             Y =  DFLOAT(NY) * 0.1d0

             CALL FDMOD (X,Y,Z,BX,BY,BZ)

C            TO FIND THE TOTAL FIELD
C            B = DSQRT(BX*BX + BY*BY + BZ*BZ)

C            TO STORE IT IN THE ARRAY
C            MAGB(NX,NY) = B

             MGZ(NX,NY) = DABS(BZ)
D            PRINT *,'BX',BX,' BY: ',BY,' BZ: ',BZ
D            PRINT *,'MGZ: ',MGZ(NX,NY)
          END DO
        END DO
          

        DO NY = -11,5
          DO NX = -9,8
       

C           FIND THE RELATIVE PERCENTAGE ERROR
            DIFF(NX,NY)=1.0d0 - (MGZ(NX,NY)/EXPT(NX,NY))
            DIFF(NX,NY)=DIFF(NX,NY) * 100.0d0

          END DO
        END DO     

        WRITE(1,70) (NX,NX=8,0,-1)
        WRITE(1,70) (NX,NX=-1,-9,-1)
        WRITE (1,*) 'EXPERIMENTAL VALUES'
        DO NY = 5,-11,-1
           WRITE(1,*) 'Y:',NY
           WRITE(1,60) (EXPT(NX,NY),NX=8,0,-1)
           WRITE(1,60) (EXPT(NX,NY),NX=-1,-9,-1)
        END DO

        WRITE(1,70) (NX,NX=8,0,-1)
        WRITE(1,70) (NX,NX=-1,-9,-1)
        WRITE(1,10)
       

        DO NY = 5,-11,-1
          WRITE(1,*) 'Y:',NY
          WRITE(1,60) (MGZ(NX,NY),NX=8,0,-1)
          WRITE(1,60) (MGZ(NX,NY),NX=-1,-9,-1)
        END DO

        WRITE(1,*)
        WRITE(1,35)  
        WRITE(1,75) (NX,NX=8,-9,-1)        
        DO NY = 5,-11,-1
           WRITE(1,*) 'Y:',NY
           WRITE(1,55) (DIFF(NX,NY),NX=8,-9,-1)
        END DO

        DO NY = 5,-11,-1
          DO NX=8,-9,-1
            DIFF1(NX,NY)=SNGL(DIFF(NX,NY))
            EXPT1(NX,NY)=SNGL(EXPT(NX,NY))
C           PRINT *,NX,NY,DIFF(NX,NY)
            MGZ1(NX,NY)=SNGL(MGZ(NX,NY))
          END DO
        END DO

        CALL WWPLOT(EXPT1,MGZ1)

 10     FORMAT (' NORMALISED VALUES')
 25     FORMAT (' ')
 30     FORMAT (' CALCULATED VALUES')
 35     FORMAT (' 1.0 - (CALCULATED/EXPT.) * 100.0')
 40     FORMAT (' EXPERIMENTAL VALUES')
 55     FORMAT (18(1X,F6.1))
 60     FORMAT (9(1X,F9.2))
 70     FORMAT (9(5X,I3,2X))
 75     FORMAT (1X,18(3X,I2,2X))

        CLOSE (1)
        CLOSE (2)
	STOP
        END
C-----------------------------------------------------------------------
C-----------------------------------------------------------------------

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