Use the Input tab of the Options > Mode Settings command or press Ctrl+M to view and/or modify the Derive state variables that affect the reading of mathematical expressions entered on the expression entry line.  The Input Settings dialog box displays the following fields:


•        Use the Input Mode field to select either character or word input mode for the names of variables and functions entered on the expression entry line.

•        Use the Case Sensitivity field to select either sensitive or insensitive case mode for the names of variables and functions entered on the expression entry line.

•        Use the Radix field to select the radix base for numbers entered on the expression entry line.  See the topic Controlling Radix BaseControlling_Radix_Base for details about setting the input and output radix base.


When a new input mode for names is selected, this command generates an expression of the form

InputMode := mode

where mode is Character or Word.  When a new case mode for names is selected, this command generates an expression of the form

CaseMode := mode

where mode is Insensitive or Sensitive.  The input and case modes can also be changed by entering on the expression entry line expressions of the above form using upper and lower case exactly as shown.


Declared variables are user variables that have been assigned a domain (see Author > Variable Domain command8MNT4Y) or a value (see Author > Variable Value command2SGW02B).  Declared functions are user functions that have been given a definition ( Author > Function Definition command1ER8JVI).  The names of declared variables and functions can be of any length and of mixed case.


Use the Input mode field of the Options > Mode Settings > Input command to select the input mode for reading variable and function names:


•        In character input mode, undeclared variables can have names consisting of only a single Latin or Greek letter (except as noted below).  If you are satisfied with such names, this input mode eliminates having to insert a space between variables being multiplied.  For example, xyz is read as the product of the variables x, y, and z.  However, if xyz is a declared variable or function, then xyz is read as that variable or function.  Character is the factory default input mode setting.

•        In word input mode, undeclared variables can have names consisting of any number of letters, digits, or underscore characters, provided they begin with a letter.  For example, in word input mode, x1, velocity, and light_years are valid multi-character variable names.  Note that word input mode requires that variable and function names be separated by a space, an operator, a function, or a parenthesis.


In either input mode, undeclared variables can have names consisting of a single letter followed by one or more underscore characters, or of an at-sign character followed by one or more decimal digits.  For example, in character or word input mode, x_ and @123 are valid variable names.


In either input mode, undeclared variables can have multi-character names consisting of any character, including spaces and mathematical operators, provided the name is enclosed in double quote marks.  These string variables provides a convenient way to include comments in Derive sessions that are saved in mth files.  For example, the following is a valid variable name:

"If x < 3, the following equation is true:"


Use the Case sensitivity field of the Options > Mode Settings > Input command to select the case mode for reading variable and function names:

•        In case sensitive mode, the case of a variable and function name entered on the expression entry line must exactly match the name given the variable or function when it was defined.  For example, entering r and R results in two distinct variables.  Note that in this mode the Built-in FunctionsBuilt_in_Functions_and_Constants must be entered using all upper-case letters.  For example, the name of the sine function must be entered as SIN.

•        In case insensitive mode, the case of a variable and function name entered on the expression entry line does not have to exactly match the name given the variable or function when it was defined.  For example, entering r and R results in the same variable whose name is r.  Also, the name of the sine function can be entered as sin, Sin, or SIN.  However, if there are two variables or functions whose names differ only in case and a name is entered that exactly matches one of the names, that variable or function is used.  Insensitive is the factory default case mode setting.


In either case mode, variable and function names are displayed in the case in which they were defined.  Also, when Greek letters are entered by clicking on the Greek symbol toolbar or by typing in their equivalent Latin name (e.g. when typing "gamma" for γ or "GAMMA" for Γ), the case of the Greek letters is always respected, even when the case of Latin letters is being ignored (i.e. when in case insensitive mode).


Click on the Reset button and then on the OK button to generate assignment statements that will restore the Derive state variables that affect the input of mathematical expressions to their factory default settings.  Click on the Reset All button to generate assignment statements that will restore all the Derive state variables to their factory default settings.  For more information about state variables see Using and Saving State VariablesUsing_and_Saving_State_Variables.


Other Algebra Window Options commandsAlgebra_Window_Options_commands 

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