Description of the program  V E L P L

     Program VELPL is designed for plotting plane sections of
slowness, phase velocity and group velocity surfaces in an arbitrary
anisotropic medium. File LU3 generated in the program ANRAY (here
named LU) contains data for the plots.

Description of input and output files
    Main input data are read from the standard input by list-directed
input (free format) and consist of a single line containing following
    'LIN' 'LOU' 'LU3'/
    'LIN' is the name of the input data file LIN.
    'LOU' is the name of the output log file LOU.
    'LU3' is the name of the input data file LU3,
          generated by program ANRAY.
    / is a slash recomended in batch and script files to enable future
Example of the main input data:
    'velpl.sch' /

    Input data consist partially of the data obtained in the program
ANRAY, which are stored in the file LU3 (here LU), and partially of the
additional data specified by the user in the file LIN. Output data
describing the computations are stored in the file LOU. The program
generates a postscript file with the desired plot.

Description of the content of the file LU3

    File LU3 contains data necessary for construction of sections of
slowness surfaces, phase velocity and group velocity surfaces
generated in the program ANRAY. The data are stored in LU3 in the
following formatted form:

1) ITYPE,NPAR,INUM                               FORMAT(16I5)

      ITYPE... ITYPE=1: qS1 wave.
                ITYPE=2: qS2 wave.
                ITYPE=3: qP wave.

      NPAR...   NPAR=1: plot of section of slowness surface.
                NPAR=2: plot of section of phase velocity surface.
                NPAR=1: plot of section of group velocity surface.

2) DDELTA,XX(I),YY(I),ZZ(I)                       FORMAT(4E15.5)

      DDELTA... angle (in radians), for which the vector (XX,YY,ZZ)
                is calculated.

      XX(I),YY(I),ZZ(I)... x,y and z components of the slowness vector
                (if NPAR=1), phase velocity vector (if NPAR=2) or
                group velocity vector (if NPAR=3) for the angle
                DDELTA. Maximum points: 300.

   The line 2 is repeated for all the angles of all the three waves.

The additional input data in the file LIN

     These data are specified by the user. They control plotting.

1) TEXT                                                FORMAT(A)

   Arbitrary alphanumerical text which is shown below the plots.

2) IPRINT,SC,SHIFT                               FORMAT(I5,2F10.5)

    IPRINT...   controls the output of some data and results into
                the file output file LOU.
                IPRINT=0: Only additional input data are reproduced.
                IPRINT=1: In addition to the previous data, the
                tables of components of the slowness vectors, phase
                velocity vectors or group velocity vectors for the
                specified angles are stored.

    SC...       scaling factor; default value SC=1.

    SHIFT...    shift between individual pictures in x direction,
                in cm. If not specified, the default value is

Example of data LIN

Termination of computations

   The computation terminates when the sections of the three waves
propagating in an anisotropic medium are plotted.
Output to the file LOU
   The file contains a copy of the input data followed by lines
containing the following information: DDELTA,V,XV,YV,ZV.
   DDELTA...  the angle (in radians), for which are the following
              values calculated.
   V...       value of the slowness (NPAR=1), phase velocity (NPAR=2)
              or group velocity (NPAR=3).
   XV,YV,ZV... components of the slowness vector, phase velocity
              or group velocity vector.