THE EGS5 CODE SYSTEM

Optional parameter modifications
The EGS5 file include/egs5 h.f is different from the other files in the include directory in that it
contains not COMMON blocks, but rather declarations and specifications of the FORTRAN parameters
used by the other EGS5 include files to define array dimensions. This is done so that users may
trivially update the dimensions of all arrays throughout the EGS5 code system simply by changing
the values of the appropriate variables in the PARAMETER statements of include/egs5 h.f. The
principal parameters defined in include/egs5 h.f which users may wish to adjust are MXMED (the
maximum number of media for the problem), MXREG (the maximum number of regions), and MXSTACK
(the maximum stack size). Most of the other parameters defined in include/egs5 h.f should be
altered only under exceptional circumstances. Some examples of parameter modifications are given
in the comments in include/egs5 h.f, as seen below:
! Maximum number of different media (excluding vacuum)
integer MXMED
parameter (MXMED = 4)
! parameter (MXMED = 10)
! Maximum number of regions allocated
integer MXREG
parameter (MXREG = 2000)
! parameter (MXREG = 2097153)
Required initializations
Two sets of initializations must be performed in the user’s MAIN program. First, MAIN must call the
EGS5 subroutine BLOCK SET to initialize common block variables not defined in BLOCK DATA. This
is done simply by including the statement:
! ==============
call block_set
! ==============
! Initialize some general variables
Also, if the user is interested in tracking the number of calls to the various subroutines of EGS5,
the counters in common block COUNTERS may also be initialized at this point by calling subroutine
COUNTERS OUT with argument 0, as in:
! ====================
call counters_out(0)
! ====================
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