Getting Started Guide

Chapter 9
Getting Started with Math

LibreOffice's Equation Editor

What is Math?

Math is LibreOffice’s component for writing mathematical equations. It is most commonly used as an equation editor for text documents, but it can also be used with other types of documents or stand-alone. When used inside Writer, the equation is treated as an object inside the text document.

Getting started

To insert an equation, choose Insert → Object → Formula.

The equation editor opens at the bottom of the screen, and the floating Elements window may appear. You will also see a small box with a gray border in your document, where the formula will be displayed.

Entering a formula

The equation editor uses a markup language to represent formulas. For example, %beta creates the Greek character beta (). This markup is designed to read similar to English whenever possible. For example, a over b produces a fraction: .

You can enter a formula in three ways:

• Select a symbol from the Elements window.

• Right-click on the equation editor and select the symbol from the context menu.

• Type markup in the equation editor.

The context menu and the Elements window insert the markup corresponding to a symbol. This provides a convenient way to learn the Math markup.

The Elements window

The simplest method for entering a formula is to use the Elements window.

The Elements window is divided into two main parts.

• The top shows the symbol categories. Click on these to change the list of symbols.

• The bottom shows the symbols available in the current category.

Example 1:

For this example we will enter a simple formula:. On the Elements window:

1. Select the top-left button of the categories (top) section.

2. Click on the multiplication symbol.

When you select the multiplication symbol on the Elements window, two things happen:

• The equation editor shows the markup:

• The body of the document shows a gray box like this:

The <?> symbols shown in Figure 4 are placeholders that you can replace by other text, for example 5 and 4. The equation will update automatically, and the result should resemble Figure 5.

Right-click menu

Another way to access mathematical symbols is to right-click on the equation editor. This pops up the menu shown in Figure 6. The items in this menu correspond exactly to those in the Elements window.

Markup

You can type the markup directly in the equation editor. For example, you can type 5 times 4 to obtain . If you know the markup, this can be the fastest way to enter a formula.

Below is a short list of common equations and their corresponding markup.

Greek characters

Greek characters (, and so on) are common in mathematical formulas. These characters are not available in the Elements window or on the right-click menu. Fortunately, the markup for Greek characters is simple: Type a % sign followed the name of the character, in English. (In localized versions of LibreOffice, these names are localized.)

• To write a lowercase character, type the name of the character in lowercase.

• To write an uppercase character, type the name of the character in uppercase.

See the table below for some examples.

Lowercase	Uppercase
%alpha	%ALPHA
%beta	%BETA
%gamma	%GAMMA
%psi	%PSI
%phi	%PHI
%theta	%THETA

Another way to enter Greek characters is by using the Symbols catalog window. Choose Tools → Catalog. Under Symbol set, select Greek and double-click on a Greek letter from the list. The markup name of the character is shown below the list window.

Example 2:

For this example we will suppose that:

• We want to enter the above formula (the value of pi rounded to 5 decimal places).

• We know the name of the Greek character (pi).

• But we do not know the markup associated with the symbol.

Step 1: Type % followed by the text pi. This displays the Greek character .

Step 2: Open the Elements window (View → Elements).

Step 3: The symbol is a relation, so we click on the Relations button. If you hover the mouse over this button you see the tooltip Relations (Figure 8).

Figure 9 shows the Elements window after clicking the Relations button. The symbol we want is circled.

Figure 8. Tooltip indicates the Relations button

Figure 9. After selecting Relations

Step 4: Click on the ab symbol. The equation editor now shows the markup %pi<?> simeq <?>.

Step 5: Delete the <?> text and add 3.14159 at the end of the equation. We end up with the markup %pi simeq 3.14159. The result is shown in Figure 10.

Customizations

Formula editor as a floating window

The formula editor can cover a large part of the Writer window. To turn the formula editor into a floating window, do this:

1. Hover the mouse over the editor frame, as shown in Figure 11.

2. Hold down the Control key and double-click.

Figure 12 shows the result. You can dock the floating window again by using the same steps. Hold down the Control key and double-click the window frame.

How can I make a formula bigger?

This is one of the most common questions people ask about Math. The answer is simple:

1. Start the formula editor and choose Format → Font size.

2. Select a larger font size under Base size (top-most entry).

The result of this change is illustrated in Figure 15.

Formula layout

The most difficult part of using Math comes when writing complicated formulas. This section provides some advice.

Brackets are your friends

Math knows nothing about order of operation. You must use brackets to state the order of operations explicitly. Consider the following example.

Markup	Result
2 over x + 1
2 over {x + 1}

Equations over more than one line

Suppose you want to type an equation covering more than one line. For example:

Your first reaction would be to simply press the Enter key. However, if you press the Enter key, though the markup goes to a new line, the resulting equation does not. You must type the newline command explicitly. This is illustrated in the table below.

Markup	Result
x = 3 y = 1
x = 3 newline y = 1

How do I add limits to my sum/integral?

The sum and int commands can (optionally) take the parameters from and to. These are used for lower and upper limits respectively. These parameters can be used singly or together. Limits for integrals are usually treated as subscripts and superscripts.

Markup	Result
sum from k = 1 to n a_k
int from 0 to x f(t) dt or int_0^x f(t) dt	or
int from Re f
sum to infinity 2^{-n}

Brackets with matrices

For background, we start with an overview of the matrix command.

Markup	Result
matrix { a # b ## c # d }

The first problem people have with matrices is that brackets do not scale with the matrix.

Markup	Result
( matrix { a # b ## c # d } )

Math provides scalable brackets. That is, the brackets grow in size to match the size of their contents. Use the commands left( and right) to make scalable brackets.

Markup	Result
left( matrix { a # b ## c # d } right)

How do I make a derivative?

Making derivatives essentially comes down to one trick: Tell Math it’s a fraction.

In other words, you have to use the over command. Combine this with either the letter d (for a total derivative) or the partial command (for a partial derivative) to achieve the effect of a derivative.

Markup	Result
{df} over {dx}
{partial f} over {partial y}
{partial^2 f} over {partial t^2}

How do I align my equations at the equals sign?

Math does not have a command for aligning equations on a particular character, but you can use a matrix to do this, as shown below.

Markup	Result
matrix{ alignr x+y # {}={} # alignl 2 ## alignr x # {}={} # alignl 2-y }

The empty braces around = are necessary because = is a binary operator and thus needs an expression on each side.

You can reduce the spacing around = if you change the inter-column spacing of the matrix:

1. With the equation editor open, choose Format → Spacing from the menu bar.

2. In the Spacing dialog (Figure 16), click the Category button and select Matrices in the drop-down menu.

3. Enter 0% for Column spacing and click OK.

Numbering equations

Equation numbering is one of Math’s best hidden features. The steps are simple:

1. Start a new line.

2. Type fn and then press F3.

The fn is replaced by a numbered formula:

Now you can double-click on the formula to edit it. For example, here is the Riemann Zeta function:

You can reference an equation (“as shown in Equation (2)”) with these steps:

1. Choose Insert → Cross-reference from the menu bar.

2. On the Cross-references tab (Figure 17), under Type, select Text.

3. Under Selection, select the equation number.

4. Under Format, select Reference.

5. Click Insert.

Done! If you later add more equations to the paper before the referenced equation, all the equations will automatically renumber and the cross-references will update.