The options mechanism allows to customise Grace to particular machine or display type and accommodate it to a given program or user. The predicate
grace_option(?Window, +Option, ?Value)inspects or modifies the option Option in the given Grace Window according to its Value argument. For example, the option font_size defines the font size for a variable matrix. Thus a call
grace_option(queens, font_size, 8)executed before the grace_matrix/2 call will display the variable matrix in a font smaller than the default 10:
Options can be specified in the initialisation file .gracerc in the current directory or in the user home directory, or directly in the program source code together with other Grace predicate calls.