How to Input Piecewise Functions

Written Tutorial

Enter Math Mode

• If you want to type a math formula, enter Math Mode first.
• For inline math, type $.
• For a display equation on its own line, use Alt/Option + $.

Insert a Piecewise Function

• In Math Mode, use the Toolbar: Insert -> Table -> Choice.
• Or press \ to enter command mode, type choice, and press Enter.

Expand the Piecewise Structure

• Place the cursor inside the piecewise function.
• Use Alt/Option + the arrow keys to expand it.

Enter Each Case

• A common layout is to type the expression on the left and the condition on the right.
• For example, type x^2 on the left and x >= 0 on the right.
• You can also keep using LEGO symbols, Tab cycling, or command mode for additional math symbols.

Numbering and Referencing

• Piecewise functions can be numbered as a whole formula or line by line.
• If you select the whole piecewise function and click 123 on the focus toolbar, the whole multi-line formula is typically numbered.
• For more about the 123 button, the \eq-number command, and references, see Quick Formula Editing.

Optional Reading: How to Write a Piecewise Function in LaTeX

In $\LaTeX$, the most common way to typeset a piecewise function is the cases environment. For example:

f(x) =
\begin{cases}
x^2, & x \ge 0 \\
-x, & x < 0
\end{cases}

This renders as:

$$f(x) = \begin{cases} x^2, & x \ge 0 \\ -x, & x < 0 \end{cases}$$

If you already have existing $\LaTeX$ code, you can also convert it directly in Liii STEM with Magic Paste.