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Description of the program  V E L P L
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     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 contains
data for the plots.

    The following CALCOMP plotting routines are required: PLOTS,        
PLOT, NUMBER and SYMBOL.

Description of input and output data
------------------------------------

    Input data consist partially of the data obtained in the program
ANRAY, which are stored in the file LU3, 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. Specification
of the files LIN, LOU and LU3 can be made through the routine SERV, 
which is part of this program package. If the routine SERV is not 
used (put 'C' in front of 'CALL SERV' in the beginning of the main 
program), the files LIN and LOU are automatically specified LIN=5, 
LOU=6, the file with plot has number 7 and the number LU3 is read 
from the file LIN, see below.

The data stored at LU3             
----------------------

    The data are stored in the file LU3 in the formatted form. For 
details see the description of the content of the file LU3 in program
ANRAY.


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) SC,ISHIFT,IPRINT,LU                          FORMAT(F10.5,4I5)

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

    ISHIFT...   shift between individual pictures in x direction, 
                in cm. If not specified, the default value is 
                ISHIFT=8.           

    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. 

    LU...       the number of the file in which ray diagrams, travel
                times and amplitudes are stored. It has no meaning
                if routine SERV is used. 

   The computation terminates when the sections of the three waves
propagating in an anisotropic medium are plotted.