Eval

Usage: eval variable = expression

      show variable ...
      set variable ...
      set variable = value
      unset variable ...
      variable = expression
      variable := expression
      external variable = expression
      external variable := expression

The "eval" statement evaluates the Fortran-77 expression and assigns the result to the variable.

The statement "show" without parameters lists the names and values of all global variables that do not have the value "NULL"; with parameters, "show" lists the names and values of the given variables. Global variables that are hidden by a local variable with the same name are identified by the attribute "hidden".

The statement "set" without parameters lists the names and values of all variables that do not have the value "NULL"; with parameters, "set" lists the names and values of the given variables. In contrast to "show", local variables are listed too.

"set variable = value" gives the variable variable the string value value.

The statement "unset" the given variables. System variables cannot be unset.

"variable = expression" and "variable := expression" are shorthand notations for "eval variable = expression" and "set variable = expression", respectively.

"external variable := value" or "external variable = value" assign a value (i. e. a string) or the result of an expression to an external (non-local) variable even if a local variable with the same name exists. This command can be used to return values from a macro to the calling macro.