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