DiaGraph has parameters on which its operation depends slightly. All the parameters have their default values, which can be changed by the user by providing the configuration file named .diagraph (or diagraph.cnf on MS-DOS). Local changes can be also made within a source file by writing a line like \a=0.3, which will be in effect only in the following lines.
the radius of a summing junction and the diameter of a forking junction, respectively
extra bottom, left, right and top margins, respectively, added to the smallest fictitious rectangle that covers all the pieces of the block diagram (that are drawn with the built-in functions other than c command); LaTeX will regard the block diagram as if it were a huge character with the size of the rectangle with the margins added
determines the position where the string specified by the c command is put; note that the subcurrent position is determined as soon as those commands referring to the value of \c are issued, and thus the value of \c should be changed before such commands are issued (it is too late to change it just before the c command is issued, even though changing the sign of \c even after the subcurrent position has been determined will lead to the corresponding effect on the action of the c command)
length of the solid line segment for a dashed box
extra length added to the solid line segment just at the head of a dashed arrow
lengths of the solid line part and blank part for a dashed arrow/ line, respectively
position of plus/ minus signs beside a summing junction; \p to the back and \v to the left, with respect to the current direction, from its center
default length for a sampler
The built-in default values of these parameters are as described in the sample configuration file .diagraph (the numbers in the brackets). If you like to change the default values, put a modified configuration file with, e.g., \a=0.3, on the directory where you are. Or, put it on the directory where your environment variable DIAGRAPH points. (Or, on the same directory as diagraph.exe, if MS-DOS.) The configuration file will be searched for in the above-mentioned order. If not found, then the built-in default values are assumed.
When changing the value of a parameter within a source file, you may write -\c, which means to change the sign of the value of \c. The default value (built-in or that given by the configuration file) can be recovered by simply writing \c. Similarly for other parameters, but some are not allowed to have negative values.
The built-in default values are designed so that they are proper when the unit length is 1cm. So, you must always specify \setlength{\unitlength}{1cm} (or another appropriate specification of the unit length that you like) in the preamble of the LaTeX file that includes the resulting output file. (Note that the default unit length of LaTeX is 1pt.)