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Default Information



Each new variable in the Equations window is assigned a guess value, lower and upper bounds, display format, and units.  These quantities can be changed using the Variable Info command in the Options menu. 


By default, every new variable has a guess value of 1.0 with lower and upper bounds of -/+ infinity.  The default display format is Auto, which directs EES to select a display format that depends on the magnitude of the variable.  However, these defaults can be changed with this command based on the first letter of the variable name.  If, for example, all variables in your equations beginning with letter T are temperatures in K, you may want to set the default guess value for T to 300, with lower and upper bounds of 0 and 1000.  You may also want to set the display to F 1 corresponding to Fixed Decimal format with 1 digit to the right of the decimal point.  Another option would be N 3 which would result in a display of 3 significant figures.  The default units for variables beginning with the letter may be entered in the units field. Units are used by EES for display purposes and in unit checking.    In addition to numerical formats, time and date formats may be set based on the first letter of the variable name.  


There are two ways to use the Default Information command.  If your problems tend to always use the same nomenclature, it is best to set the variable once and for all with the Store button.  The Store button will cause the variable defaults to be permanently saved so that they will be in effect at the  start of the program the next time EES is run.  The Default Information command can also be used to selectively change the information for existing variables.  For example, if you set the  units for variables beginning with T to K in the Default Information dialog and select the OK button, then all existing variables that begin with letter T will be changed to have units of K.  Only the changes made in the Default Information dialog will be applied to existing variables.  


The Store button can be used in two ways.  In either case, a dialog will appear in which a file name can be entered.  If the file name extension is .DVI (Default Variable Information), EES will store the guess value, bounds and format as a function of the first letter of the variable name.  The .DVI files created in this way can be read when the Load button.  Alternatively, if the file name extension is .prf, the default variable information and all other defaults will be saved in an EES Preferences (*.prf) file.   Note that all default information including the unit system and tolerances, as well as the specifications in the Preferences dialog are stored in the .prf file in the working directory.   The EES.prf file is automatically loaded when EES is started.  An existing .PRF file in any directory can be loaded with the Load button in the Preferences dialog or with a $INCLUDE directive.


The OK button sets the current default setting for this problems session only.