C 
C Program LINDEN to densify lines
C
C Version: 5.40
C Date: 2000, February 21
C
C Coded by Petr Bulant
C     Department of Geophysics, Charles University Prague,
C     Ke Karlovu 3, 121 16 Praha 2, Czech Republic,
C     E-mail: bulant@seis.karlov.mff.cuni.cz
C
C Program LINDEN reads the line(s) specified in the form
C LIN, and divides each part of each
C line into NLINDEN subparts (i.e. adds NLINDEN-1 new points in
C between each two subsequent points of each line). The subparts of
C each part are of the same length (the new points are added
C equidistantly).
C
C.......................................................................
C                                                    
C Description of data files:
C
C Input data read from the standard input device (*):
C     The data are read by the list directed input (free format) and
C     consist of a single string 'SEP':
C     'SEP'...String in apostrophes containing the name of the input
C             SEP parameter or history file with the input data.
C     No default, 'SEP' must be specified and cannot be blank.
C
C                                                     
C Input data file 'SEP':
C     File 'SEP' has the form of the SEP
C     parameter file.  The parameters, which do not differ from their
C     defaults, need not be specified in file 'SEP'.
C Names of input and output files:
C     LIN='string'... Name of the input file with the input line(s).
C             Description of file LIN
C             Default: LIN='lin.dat'
C     LINOUT='string'... Name of the output file with the densified
C             line(s). Description of file LINOUT
C             Default: LINOUT='lin.out'
C Data specifying the form of the output file:
C     NLINDEN=integer ... Number of subparts, to which each part of the
C             input line is to be divided.
C             Default: NLINDEN=1 (No new points added)
C                                                     
C Input file LIN with the lines:
C (1) None to several strings terminated by / (a slash)
C (2) For each line data (2.1), (2.2) and (2.3):
C (2.1) 'NAME',X1,X2,X3,/
C     'NAME'... Name of the line.  Not considered.  May be blank but
C             must be different from '$'.
C     X1,X2,X3... Optional coordinates of the reference point of the
C             line.  Not considered. Need not be defined, but must
C             must be different from the value of UNDEF
C             (the deffinition of the parameter UNDEF see below).
C     /...    List of values must be terminated by a slash.
C (2.2) For each point of the line data (2.2.1):
C (2.2.1) X1,X2,X3,V1,...,VN,/
C     X1,X2,X3... Coordinates of the point of the line.
C             X1 must be different from the value of UNDEF
C             (the deffinition of the parameter UNDEF see below).
C             Default for X2 and X3 is 0.
C     V1,...,VN...Other real values. Not considered. Up to 100 values
C             is allowed.
C     /...    List of values must be terminated by a slash.
C (2.3) /
C (3) / or end of file.
C
C                                                  
C Output file LINOUT with the densified lines:
C (1) Strings as in file LIN terminated by / (a slash). Only the
C     first 20 strings from file LIN are written to file LINOUT. Each
C     line contains only one string or the final /. Spaces at the ends
C     of the strings are not written.
C (2) For each line data (2.1), (2.2) and (2.3):
C (2.1) 'NAME',X1,X2,X3,/
C     Name of the line and the optional coordinates as in the file LIN.
C (2.2) For each point of the line data (2.2.1):
C (2.2.1) X1,X2,X3,/
C     Coordinates of the point of the line. Points from file LIN are
C     repeated, NLINDEN-1 new points is added equidistantly in between
C     each pair of subsequent points from file LIN.
C (2.3) / (a slash)
C (3) / (a slash) at the end of file.
C
C-----------------------------------------------------------------------
C Subroutines and external functions required:
      EXTERNAL ERROR,RSEP1,RSEP3T,RSEP3I,FORM1,LENGTH
      INTEGER  LENGTH
C     ERROR ... File error.for.
C     RSEP1,RSEP3T,RSEP3I ...
C             File sep.for.
C     FORM1 ... File forms.for.
C     LENGTH ... File length.for.
C
C
C     Filenames and parameters:
      CHARACTER*80 FSEP,FIN,FOUT
      INTEGER LU1,LU2,NDEN,NDEN1
      REAL UNDEF
      PARAMETER (LU1=1,LU2=2,UNDEF=-999999.)
C
C     Other variables:
      CHARACTER*(24) FORMAT
      INTEGER I1,I2,I
      REAL R1,R2,R3,X1,X2,X3,Y1,Y2,Y3,Z1,Z2,Z3,DX1,DX2,DX3,DEN,V(100)
      CHARACTER*255 TEXT(20)
      DATA  TEXT/20*'$'/
C
C.......................................................................
C
C     Reading a name of the file with the input data:
      FSEP=' '
      WRITE(*,'(A)') ' LINDEN: Enter input filename: '
      READ(*,*) FSEP
      IF (FSEP.EQ.' ') THEN
C       LINDEN-01
        CALL ERROR('LINDEN-01: No input file specified')
C       Input file in the form of the SEP (Stanford Exploration Project)
C       parameter or history file must be specified.
C       There is no default filename.
      ENDIF
      WRITE(*,'(A)') '+LINDEN: Working ...           '
C
C     Reading all the data from the SEP file into the memory:
      CALL RSEP1(LU1,FSEP)
C
C     Reading input and output filenames:
      CALL RSEP3T('LIN'   ,FIN ,'lin.dat')
      CALL RSEP3T('LINOUT',FOUT,'lin.out')
      CALL RSEP3I('NLINDEN',NDEN,1)
      NDEN=IABS(NDEN)
      DEN=FLOAT(NDEN)
      NDEN1=0
      IF (NDEN.NE.0) NDEN1=NDEN-1
C
C     Beginning of the output file:
      OPEN(LU2,FILE=FOUT)
C
C     Reading lines:
      OPEN(LU1,FILE=FIN,STATUS='OLD')
      READ(LU1,*) (TEXT(I),I=1,20)
      I2=0
      DO 10, I1=20,1,-1
        IF (TEXT(I1).NE.'$') THEN
          I2=I1
          GOTO 11
        ENDIF
  10  CONTINUE
  11  CONTINUE
      DO 20, I1=1,I2
        WRITE(LU2,'(3A)')  '''',TEXT(I1)(1:LENGTH(TEXT(I1))),''''
  20  CONTINUE
      WRITE(LU2,'(A)')  '/'
C     Loop over lines:
   60 CONTINUE
        TEXT(1)='$'
        R1=UNDEF
        R2=UNDEF
        R3=UNDEF
        READ(LU1,*,END=90) TEXT(1),R1,R2,R3
        IF (TEXT(1).EQ.'$') GOTO 90
        FORMAT(1:6)='(3A,0('
        FORMAT(15:16)='))'
        IF     (R1.EQ.UNDEF) THEN
          WRITE(LU2,'(3A)')
     *      '''',TEXT(1)(1:LENGTH(TEXT(1))),''' /'
        ELSEIF (R2.EQ.UNDEF) THEN
          CALL FORM1(R1,R1,FORMAT(7:14))
          FORMAT(5:5)='1'
          WRITE(LU2,FORMAT)
     *      '''',TEXT(1)(1:LENGTH(TEXT(1))),''' ',R1,' /'
        ELSEIF (R3.EQ.UNDEF) THEN
          CALL FORM1(AMIN1(R1,R2),AMAX1(R1,R2),FORMAT(7:14))
          FORMAT(5:5)='2'
          WRITE(LU2,FORMAT)
     *      '''',TEXT(1)(1:LENGTH(TEXT(1))),''' ',R1,' ',R2,' /'
        ELSE
          CALL FORM1(AMIN1(R1,R2,R3),AMAX1(R1,R2,R3),FORMAT(7:14))
          FORMAT(5:5)='3'
          WRITE(LU2,FORMAT)
     *      '''',TEXT(1)(1:LENGTH(TEXT(1))),''' ',R1,' ',R2,' ',R3,' /'
        ENDIF
C       Reading the line points
        X1=UNDEF
        X2=0.
        X3=0.
        READ(LU1,*,END=80) X1,X2,X3,(V(I1),I1=1,100)
        IF (X1.EQ.UNDEF) GOTO 80
        FORMAT(1:3)='(3('
        FORMAT(12:13)='))'
        CALL FORM1(AMIN1(X1,X2,X3),AMAX1(X1,X2,X3),FORMAT(4:11))
        WRITE(LU2,FORMAT) X1,' ',X2,' ',X3,' /'
   70   CONTINUE
          Y1=UNDEF
          Y2=0.
          Y3=0.
          READ(LU1,*,END=80) Y1,Y2,Y3,(V(I1),I1=1,100)
          IF (Y1.EQ.UNDEF) GOTO 80
          IF (NDEN1.NE.0) THEN
            DX1=(Y1-X1)/DEN
            DX2=(Y2-X2)/DEN
            DX3=(Y3-X3)/DEN
            DO 75, I1=1,NDEN1
              Z1=X1+I1*DX1
              Z2=X2+I1*DX2
              Z3=X3+I1*DX3
              CALL FORM1(AMIN1(Z1,Z2,Z3),AMAX1(Z1,Z2,Z3),FORMAT(4:11))
              WRITE(LU2,FORMAT) Z1,' ',Z2,' ',Z3,' /'
   75       CONTINUE
          ENDIF
          CALL FORM1(AMIN1(Y1,Y2,Y3),AMAX1(Y1,Y2,Y3),FORMAT(4:11))
          WRITE(LU2,FORMAT) Y1,' ',Y2,' ',Y3,' /'
          X1=Y1
          X2=Y2
          X3=Y3
        GOTO 70
   80   CONTINUE
C       End of line.
        WRITE(LU2,'(A)') ' /'
      GOTO 60
   90 CONTINUE
C     End of file.
      WRITE(LU2,'(A)') ' /'
      CLOSE(LU1)
      CLOSE(LU2)
      WRITE(*,'(A)') '+LINDEN: Done.                 '
      STOP
      END
C
C=======================================================================
C
      INCLUDE 'error.for'
C     error.for
      INCLUDE 'sep.for'
C     sep.for
      INCLUDE 'length.for'
C     length.for
      INCLUDE 'forms.for'
C     forms.for
C
C=======================================================================
C