User Guide

Page 2-20
The expression tree
The expression tree is a diagram showing how the Equation Writer interprets
an expression. See Appendix E for a detailed example.
The CURS function
The CURS function (@CURS) in the Equation Writer menu (the B key) converts
the display into a graphical display and produces a graphical cursor that can
be controlled with the arrow keys (š™—˜) for selecting sub-
expressions. The sub-expression selected with @CURS will be shown framed in
the graphics display. After selecting a sub-expression you can press ` to
show the selected sub-expression highlighted in the Equation writer. The
following figures show different sub-expressions selected with and the
corresponding Equation Writer screen after pressing `.
Editing algebraic expressions
The editing of algebraic equations follows the same rules as the editing of
algebraic equations. Namely:
• Use the arrow keys (š™—˜) to highlight expressions
• Use the down arrow key (˜), repeatedly, to trigger the clear editing
cursor . In this mode, use the left or right arrow keys (š™) to
move from term to term in an expression.