c LINER
      SUBROUTINE LINER (X1,Y1,X2,Y2,NUM1,NUM2)
C======================================================================C
C                                                                      C
C     SUBROUTINE : LINER                                               C
C                                                                      C
C     PURPOSE:                                                         C
C                                                                      C
C     THIS SUBROUTINE DOES A TWO-DIMENSIONAL LINEAR FIT USING THE      C
C     LOCATIONS STORED IN ANOTHER ARRAY.                               C
C                                                                      C
C     USE:                                                             C
C            CALL LINER (X1,Y1,X2,Y2,NUM1,NUM2)                        C
C                                                                      C
C     PARAMETERS :                                                     C
C                                                                      C
C            X1     THE X COORDINATES OF THE KNOWN ARRAY               C
C                                                                      C
C            Y1     THE Y COORDINATES OF THE KNOWN ARRAY               C
C                                                                      C
C            X2     THE X POSITION OF THE ARRAY THAT HOLDS THE         C
C                   LOCATION OF THE LINEAR FIT POINTS                  C
C                                                                      C
C            Y2     THE LINEAR FIT POSITION CORRESPONDING TO X2        C
C                                                                      C
C            NUM1   THE NUMBER OF POINTS IN X1,Y1 ARRAYS               C
C                                                                      C
C            NUM2   THE NUMBER OF POINT TO BE FITTED IN THE X1 ARRAY   C
C                                                                      C
C     SOURCE:       DONALD J. RICHARDSON                               C
C                   (SYSTEM AND APPLIED SCIENCES CORPORATION)          C
C                                                                      C
C     LANGUAGE:     FORTRAN 5                                          C
C                                                                      C
C     LATEST REVISION:     December 15, 1991                           C
C                                                                      C
C======================================================================C
      DIMENSION X1(NUM1),Y1(NUM1),X2(NUM2),Y2(NUM2)
      ILOOK=1
      IF (NUM1.LE.1) THEN
             PRINT*,'NOT ENOUGH POINTS TO DO A LINEAR INTEPOLATION'
            STOP 'TOO FEW DATA POINTS IN LINER FOR INTERPOLATION'
      END IF
      DO 100 I=1,NUM1 - 1
100   IF (X1(I).NE.X1(I + 1)) GO TO 110
      PRINT*,'ALL OF THE ORDINATE VALUE FOR LINER WERE THE SAME'
      print*,'num1 =', num1
      do i=1,num1
	print*,x1(i),y1(i)
      end do
      STOP 'X ARRAY IDENTICAL IN LINER'
110   IUPDWN=SIGN(1.,X1(NUM1) - X1(I))                !modified 12/15/91
      INDX1=(IUPDWN+1)/2
      INDX2=1-INDX1
      DO 20 I=1,NUM2
C ***
C     THE SECTION POSTIONS THE X2 ARRAY
C ***
5     IF (NUM1.GT.ILOOK) THEN
             IF(X2(I).GT.X1(ILOOK+INDX1).OR.X2(I).LT.X1(ILOOK+INDX2))
     1              THEN
                    ILOOK=ILOOK + IUPDWN * SIGN(1.,X2(I)-X1(ILOOK+1))
                    IF (ILOOK.LT.1) THEN
                           ILOOK=1
                           GO TO 10
                    END IF
                    GO TO 5
             END IF
      ELSE
             ILOOK=NUM1-1
      END IF
C ***
C     DO THE LINEAR INTERPOLATION
C ***
10    IF (X1(ILOOK).EQ.X1(ILOOK+1)) THEN
             Y2(I)=(Y1(ILOOK)+Y1(ILOOK+1))*.5
      ELSE
             Y2(I)=(Y1(ILOOK)*(X2(I)-X1(ILOOK+1))+Y1(ILOOK+1)*(X1(ILOOK)
     1             -X2(I)))/(X1(ILOOK)-X1(ILOOK+1))
      ENDIF
20    CONTINUE
      RETURN
      END
c
cLINERD
      SUBROUTINE LINERD (X1,Y1,X2,Y2,NUM1,NUM2)
C======================================================================C
C                                                                      C
C     SUBROUTINE : LINER                                               C
C                                                                      C
C     PURPOSE:                                                         C
C                                                                      C
C     THIS SUBROUTINE DOES A TWO-DIMENSIONAL LINEAR FIT USING THE      C
C     LOCATIONS STORED IN ANOTHER ARRAY.                               C
C                                                                      C
C     USE:                                                             C
C            CALL LINER (X1,Y1,X2,Y2,NUM1,NUM2)                        C
C                                                                      C
C     PARAMETERS :                                                     C
C                                                                      C
C            X1     THE X COORDINATES OF THE KNOWN ARRAY               C
C                                                                      C
C            Y1     THE Y COORDINATES OF THE KNOWN ARRAY               C
C                                                                      C
C            X2     THE X POSITION OF THE ARRAY THAT HOLDS THE         C
C                   LOCATION OF THE LINEAR FIT POINTS                  C
C                                                                      C
C            Y2     THE LINEAR FIT POSITION CORRESPONDING TO X2        C
C                                                                      C
C            NUM1   THE NUMBER OF POINTS IN X1,Y1 ARRAYS               C
C                                                                      C
C            NUM2   THE NUMBER OF POINT TO BE FITTED IN THE X1 ARRAY   C
C                                                                      C
C     SOURCE:       DONALD J. RICHARDSON                               C
C                   (SYSTEM AND APPLIED SCIENCES CORPORATION)          C
C                                                                      C
C     LANGUAGE:     FORTRAN 5                                          C
C                                                                      C
C     LATEST REVISION:     December 15, 1991                           C
C                                                                      C
C======================================================================C
      IMPLICIT REAL*8 (A-H,O-Z)
      DIMENSION X1(NUM1),Y1(NUM1),X2(NUM2),Y2(NUM2)
      ILOOK=1
      IF (NUM1.LE.1) THEN
             PRINT*,'NOT ENOUGH POINTS TO DO A LINEAR INTEPOLATION'
            STOP 'TOO FEW DATA POINTS IN LINER FOR INTERPOLATION'
      END IF
      DO 100 I=1,NUM1 - 1
100   IF (X1(I).NE.X1(I + 1)) GO TO 110
      PRINT*,'ALL OF THE ORDINATE VALUE FOR LINER WERE THE SAME'
      STOP 'X ARRAY IDENTICAL IN LINER'
110   IUPDWN=SIGN(1.D0,X1(NUM1) - X1(I))              !modified 12/15/91
      INDX1=(IUPDWN+1)/2
      INDX2=1-INDX1
      DO 20 I=1,NUM2
C ***
C     THE SECTION POSTIONS THE X2 ARRAY
C ***
5     IF (NUM1.GT.ILOOK) THEN
             IF(X2(I).GT.X1(ILOOK+INDX1).OR.X2(I).LT.X1(ILOOK+INDX2))
     1              THEN
                    ILOOK=ILOOK + IUPDWN*SIGN(1.D0,X2(I)-X1(ILOOK+1))
                    IF (ILOOK.LT.1) THEN
                           ILOOK=1
                           GO TO 10
                    END IF
                    GO TO 5
             END IF
      ELSE
             ILOOK=NUM1-1
      END IF
C ***
C     DO THE LINEAR INTERPOLATION
C ***
10    IF (X1(ILOOK).EQ.X1(ILOOK+1)) THEN
             Y2(I)=(Y1(ILOOK)+Y1(ILOOK+1))*.5
      ELSE
             Y2(I)=(Y1(ILOOK)*(X2(I)-X1(ILOOK+1))+Y1(ILOOK+1)*(X1(ILOOK)
     1             -X2(I)))/(X1(ILOOK)-X1(ILOOK+1))
      ENDIF
20    CONTINUE
      RETURN
      END