Expression editor

Typing the shortcut Alt-e or using the menu Expression->New expression will open an expression editor above the current level. The scientific keyboard should automatically appear (press the button at the top right of the keyboard if you don't want it).

The expression editor lets you enter complex mathematical expression in 2-d like on a paper. For example suppose we want to enter

$$\left(\vphantom{\frac{x+1}{x+2}}\right.$$$${\frac{{x+1}}{{x+2}}}$$$$\left.\vphantom{\frac{x+1}{x+2}}\right)$$ ^. $$\left(\vphantom{3+\frac{4}{x} }\right.$$3 + $${\frac{{4}}{{x}}}$$$$\left.\vphantom{3+\frac{4}{x} }\right)^{5}_{}$$

Open an expression editor (Alt-e) then type

• x + 1  $\uparrow$, this will select x + 1
• / (for the division)
• x + 2  $\uparrow$   $\uparrow$
• * 3 $\uparrow$ + 4 $\uparrow$ / x
• $\uparrow$   $\uparrow$   $\uparrow$ ^ 5

You can now move the selection in the tree of the expression with the arrows keys :

• $\uparrow$ moves up one level in the tree, that is select the function or operator with had the current selection as argument (it also selects the other arguments of the function/operator)
• $\downarrow$ moves down one level in the three, that is select the first argument of the function/operator of the current selection
• $\leftarrow$ or $\rightarrow$ select the left or right brother of the current selection
• Ctrl- $\leftarrow$ or Crtl- $\rightarrow$ exchange the current selection with it's left or right brother

Another example, let's enter

$$\int_{0}^{{+\infty}}$$$${\frac{{1}}{{1+x^2}}}$$

Type Alt-e to open a new expression editor

• the $\int$ key on the scientific keyboard or Ctrl-S on the keyboard, we now have an undefined integral
• the , key will switch to a defined integral (to do the reverse operation, one would select each bound and press the backspace key)
• $\downarrow$, replace 0 by the function 1/(1+x^2) and $\uparrow$
• $\leftarrow$ to select the upper bound
• the $\infty$ key on the scientific keyboard to replace the 1
• the Enter key to evaluate the integral

We know list the other special keys in the expression editor:

• ,: if a sequence is selected, add a 0 to the end of the sequence and select it. If the selection is not a sequence, creates a sequence of size 2 with first element the selection, init the second element to 0 and select it. You can move the newly created 0 in the sequence with Ctrl- $\rightarrow$ and Ctrl- $\leftarrow$.
• (: if a sequence is selected, make a user function applied to this sequence, the name of the user function is initialized to f and selected (type the function name to replace the f by your function name). If a vector is selected, it is replaced by a sequence.
• [: if a sequence is selected, it is replaced by a vector, if a vector is selected, an indexed vector/matrix position is created where the variable name of the vector/matrix is initialized to m and selected (type the matrix/list name to replace m)
• keys in combination with the Ctrl key
  • Ctrl-A: select All
  • Ctrl-C: Copy selection to clipboard (like under windows)
  • Ctrl-V: Paste selection from clipboard
  • Ctrl-T: translate selection to L^ATEX and copy to clipboard (the translation is also copied to the Msg output, click on the Msg button to make it visible or not)
  • Ctrl-E: eval selection
  • Ctrl-F: factor selection
  • Ctrl-N: apply normal on selection
  • Ctrl-P: apply partfrac on selection
  • Ctrl-I (or Tab key) completion key (position in index at the function whose name begins the same)
  • Ctrl-S: integral
  • Ctrl-L: limit
  • Ctrl-D: derivative
  • Ctrl-Z: undo
  • Ctrl-Y: redo