• Undefine any or all variables.

The "clear" command is used to erase the definition of any specified variables.  The keyword "all" can be used to erase all variable definitions.

The "clear" command does not work for "lock"ed variables...  A variable must be "unlock"ed for its value to be cleared.

Note:  Since equations automatically solve for their unknowns, some cleared variables might be automatically re-defined immediately!  That behavior guarantees the consistency and validity of all variable definitions.

e.g.   z=2x-7y     Enter a simple equation.
       z=5         Define one of the three unknowns.
       x=9         Define a second unknown. "y" gets evaluated.
       clear x     "x" is cleared, but re-defined automatically!
       clear y z   Clear two of the three variables.
       clear all   Clear all of the evaluated variables.