SUBROUTINE BINSRH(XBRK,YBRK,NBRK,X,Y)
C
           IMPLICIT NONE
C
C          THIS IS A BINARY SEARCH ALGORITHM
C          THE ALGORITHM LOCATES THE APPROPRIATE TABLE
C          ELEMENTS FOR THE ABSCISSA (XBRK), AND USES LINEAR
C          INTERPOLATION TO SOLVE FOR THE ORDINATE  Y.
C
       DOUBLE PRECISION   XBRK(*),YBRK(*), X, Y
       DOUBLE PRECISION   XMIN, XMAX
       INTEGER NBRK, NMAX, NMIN, NTOP, NBOT, NHALF
       EXTERNAL INTERPL
C
C     CHECK FOR OVERRANGE ON THE TABLE
C
       XMIN = XBRK(1)
       XMAX = XBRK(NBRK) 
      IF(X.LT.XBRK(1).OR.X.GT.XBRK(NBRK))  THEN
C    
c       WRITE(99,100)  XBRK(1),XBRK(NBRK),X
       PRINT100,  XBRK(1),XBRK(NBRK),X
  100 FORMAT(1X,'VALUE OF X IS OUTSIDE OF TABLE'/1X,
     +'XMIN,XMAX,X=',3(F11.4,1X)/)
C     
       IF(X.LT.XBRK(1) )  THEN
       WRITE(99,*) ' X LESS THAN XMIN TABLE VALUE'
       WRITE(99,*) 'VALUE OF XMIN IS USED' 
       X=XMIN
       ELSE
       WRITE(99,*) ' X GREATER THAN XMAX TABLE VALUE'
       WRITE(99,*) ' VALUE OF XMAX IS USED'
       X=XMAX
       ENDIF
C       
       ENDIF
C      NOTE: TABLE MUST BE IN ASCENDING ORDER FOR THE
C      ABSCISSA
C
C      INITIALIZE
       NBOT=1
       NTOP=NBRK
C
C      BEGIN SEARCH
C
  10   NHALF=(NTOP-NBOT)/2+NBOT
       IF(XBRK(NBOT).LE.X.AND.X.LE.XBRK(NHALF)) THEN
C
       NBOT=NBOT
       NTOP=NHALF
C
       ELSE
C
       NBOT=NHALF
       NTOP=NTOP
C
       ENDIF
       IF((NBOT+1).LT.NTOP)   THEN
       GO  TO  10
       ENDIF
C
C          INTERPOLATE OFF OF RESULTS
      NMAX=NTOP
      NMIN=NBOT
C
      CALL  INTERPL(XBRK,YBRK,NMIN,NMAX,X,Y)
C
  99  CONTINUE
C
      RETURN
      END
C
C
C
      SUBROUTINE INTERPL(XBRK,YBRK,NMIN,NMAX,X,Y)
C
      IMPLICIT NONE
C      
C     SUBROUTINE PERFORMS LINEAR INTERPOLATION ON THE INPUT
C     ARRAY'S--XBRK ARE THE ABSCISSA AND YBRK ARE
C     THE ORDINATE
      DOUBLE PRECISION  XBRK(*),YBRK(*), X, Y, X1, X2, Y1, Y2, SLOPE
      INTEGER NMIN, NMAX
C
      X1=XBRK(NMIN)
      X2=XBRK(NMAX)
C
      Y1=YBRK(NMIN)
      Y2=YBRK(NMAX)
C
      SLOPE=(Y2-Y1)/(X2-X1)
      Y=(X-X1)*SLOPE+Y1
C
      RETURN
      END
C
C
C