Precompilation

X-PLOR is written in standard FORTRAN-77, with the exception of the following statements:

 DO <do-loop-counter>     
   <FORTRAN-statements>
 END DO 

 DO UNTIL (<logical expression>)     
   <FORTRAN-statements>
 END DO 

 DO WHILE (<logical expression>)            
   <FORTRAN-statements>
 END DO

 INCLUDE `filename'                    

 IMPLICIT NONE

The meaning of these statements is self-evident. They are converted to standard FORTRAN-77 by the PREXPLOR precompiler. In addition, the inclusion of common block files with the INCLUDE statement is carried out by the PREXPLOR precompiler. The PREXPLOR precompiler also modifies the array dimensions of X-PLOR if this is desired. PREXPLOR reads the dimensioning information from a single file (``prexplor.dim") that contains the dimensioning parameters one wants to modify. In addition, PREXPLOR changes the variables of X-PLOR from single to double precision or from double to single, depending on the machine. There are special versions of PREXPLOR available for the machines mentioned below.

A printing option to make a printout of the source code utilizes the command file ``pretty.com".