UN-DEFINE VARIABLE

Program variables are created by the DEFINE VARIABLE (see Section 15.26, Page ) and VARIABLE commands, and automatically by various commands e.g. STATISTICS. As the variable translation table is of a finite size³² and since the DEFINE VARIABLE and VARIABLE automatically pole through the defined variable names as default suggestions, it can be useful to be able to remove variables.

UN-DEFINE VARIABLE allows variables to be removed from the translation table. If no variables exist a warning message is returned. If one or more variables exist, the user is prompted for the ``name'' of the variable to be removed. One of the existing variables will be proposed as a default.

The following text shows an example of defining a number of variables automatically using the STATISTICS commands, and then removing all of the variables until none are left.

Main menu: ENTER COMMAND [INPUT DATA]:stat
Statistics of the Region of Interest (ROI):
  DC limits: Min (    .50     ,    .50    ) Max (  100.     ,   100.    )
  Pixel number limits: Min (     1 ,     1) Max (  100 ,   100)
  Total number of data values =    100 *    100 =        10000
  Minimum data value =    75.00000
  Maximum data value =    1074.000
  Average (mean) data value =    511.5939
  Sum of data values =    5115939.
  Root mean square (RMS) value =    574.2042
  Standard deviation value =    260.7468
  Skewness parameter =    .1356223
Main menu: ENTER COMMAND [CLOSE LOG]:un-define
ENTER VARIABLE NAME [##MINIMUM]:
Main menu: ENTER COMMAND [MACRO]:un-define
ENTER VARIABLE NAME [##MAXIMUM]:
Main menu: ENTER COMMAND [MACRO]:un-define
ENTER VARIABLE NAME [##MEAN]:
Main menu: ENTER COMMAND [MACRO]:un-define
ENTER VARIABLE NAME [##RMS]:
Main menu: ENTER COMMAND [MACRO]:un-define
ENTER VARIABLE NAME [##SIGMA]:
Main menu: ENTER COMMAND [MACRO]:un-define
ENTER VARIABLE NAME [##SKEWNESS]:
Main menu: ENTER COMMAND [MACRO]:un-define
ENTER VARIABLE NAME [##TOTAL]:
Main menu: ENTER COMMAND [MACRO]:un-define
WARNING: No variables are presently defined so you cannot "UN-DEFINE" any
Main menu: ENTER COMMAND [MACRO]:close