C SUBROUTINE FILE 'VARNUL.FOR' - EMPTY SUBROUTINES VAR1 TO VAR6.
C
C BY LUDEK KLIMES
C
C SUBROUTINE VAR1 AND ITS ENTRIES VAR2, VAR3, VAR4 AND VAR5 ARE CALLED
C FROM THE MODEL SPECIFICATION SUBROUTINES IN ORDER TO KEEP IN THE
C MEMORY VARIATIONS OF THE FUNCTIONS DESCRIBING THE MODEL, WITH RESPECT
C TO THEIR COEFFICIENTS.  THE VARIATIONS ARE REQUIRED FOR THE
C TRAVEL-TIME INVERSION OF THE MODEL AND ARE RECALLED FROM THE MEMORY BY
C CALLING THE ENTRY VAR6, SEE THE SUBROUTINE FILE 'VAR.FOR'.  IN THE
C CASE OF FORWARD MODELLING, THE INVOCATION OF SUBROUTINES VAR1, VAR2,
C VAR3, VAR4 AND VAR5 IS USELESS.
C
C IN THE CASE OF FORWARD MODELLING, EITHER:
C     THE COMPLETE RAY TRACING PROGRAM MAY BE LINKED WITH THE EMPTY
C     SUBROUTINES OF THIS FILE,
C OR:
C     USER MAY REMOVE THE INVOCATIONS OF THE SUBROUTINES VAR1, VAR2,
C     VAR3, VAR4 AND VAR5 FROM THE MODEL SPECIFICATION SUBROUTINE FILES.
C     THIS OPTION SAVES THE CPU TIME WITH RESPECT TO THE FORMER ONE.
C     IN THE BASIC VERSION OF C.R.T. ROUTINES, SUBROUTINES VAR* ARE
C     CALLED FROM THE FOLLOWING SUBROUTINE FILES:
C             'MODEL.FOR' 7 TIMES (IN SUBROUTINES VELOC AND POWER),
C             'PARM.FOR'  7 TIMES (IN SUBROUTINE PARM2),
C             'VAL.FOR'  21 TIMES (IN SUBROUTINE VAL2),
C             'FIT.FOR'   3 TIMES (IN SUBRS. CURVBD, SURFBD AND VAL3BD).
C     NOTE THAT THE CORRESPONDING CALL STATEMENTS CONTAIN THE SUBSTRING
C             '     CALL VAR', AND ARE DENOTED BY 'V' IN THE FIRST
C             COLUMN OF THE DISTRIBUTED SOURCE CODE.
C     ATTENTION: THERE IS A CONTINUATION LINE OF SUCH A CALL STATEMENT
C     IN THE FILE 'FIT.FOR'.
C
C ERROR MESSAGES:
C     360...  ERROR IN VAR6: NO VARIATIONS STORED:
C             MODEL-TREATING SUBROUTINE FILES ARE LINKED WITH THE
C             DUMMY SUBROUTINE FILE 'VARNUL.FOR' INSTEAD OF 'VAR.FOR'.
C             NO VARIATIONS ARE STORED IN THE MEMORY, THUS THE ENTRY
C             VAR6 CANNOT BE CALLED.
C
C DATE: 1992, DECEMBER 3
C CODED BY LUDEK KLIMES
C
C-----------------------------------------------------------------------
C
      SUBROUTINE VAR1()
C     DUMMY ARGUMENTS OF ALL ENTRIES:
      INTEGER IBI,IBB,IVAL,IVAL0,II,IEND
      REAL B0I,B1I,B2I,B3I,BBI
C
      ENTRY VAR2(IBI,B0I,B1I,B2I,B3I)
C
      ENTRY VAR3(IBI)
C
      ENTRY VAR4(IBB,BBI)
C
      ENTRY VAR5(IVAL,IVAL0)
      RETURN
C
      ENTRY VAR6(IVAL,II,IEND,IBI,B0I,B1I,B2I,B3I)
      PAUSE 'ERROR 360 IN VAR6: NO VARIATIONS STORED'
      STOP
      RETURN
      END
C
C=======================================================================
C
