# Operators

You can choose among various operators to structure your LibreOffice Math formula. All available operators appear in the lower part of the Elements pane. They are also listed in the context menu of the Commands window. All operators not contained in the Elements pane or in the context menu must be typed manually in the Commands window.

The following is a list of the available operators. An icon next to the operator name indicates that it can be accessed through the Elements pane (choose View - Elements) or through the context menu of the Commands window.

### Operator Functions

Limit

Inserts the limit sign with one placeholder. You can also enter lim <?> directly in the Commands window.

Summation

Inserts a summation sign with one placeholder. You can also enter sum <?> directly in the Commands window.

Product

Inserts a product sign with one placeholder. You can also type prod <?> directly in the Commands window.

Coproduct

Inserts a coproduct symbol with one placeholder. You can also enter coprod <?> directly in the Commands window.

Upper and Lower Limit

Inserts a range statement upper and lower limit for integral and summation with one placeholder. You can also type from{<?>} to{<?>} <?> directly in the Commands window. Limit statements must be combined with the appropriate operators. The limits will be centred above/below the summation character.

Integral

Inserts an integral sign with one placeholder. You can also type int <?> directly in the Commands window.

Double Integral

Inserts a double integral symbol with one placeholder. You can also type iint <?> directly in the Commands window.

Triple Integral

Inserts a triple integral sign with one placeholder. You can also type iiint <?> directly in the Commands window.

Lower Limit

Inserts a lower limit range statement for integral and sum with placeholders. You can also type from {<?>}<?> directly in the Commands window.

Curve Integral

Inserts a curve integral symbol with one placeholder. You can also type lint <?> directly in the Commands window.

Double Curve Integral

Inserts a double curve integral symbol with one placeholder. You can also type llint <?> directly in the Commands window.

Triple Curve Integral

Inserts a triple curve integral sign with one placeholder. You can also type lllint <?> directly in the Commands window.

Upper Limit

Inserts the range statement upper limit for integral and summation with placeholders You can also type to <?><?> directly in the Commands window. Limit statements can only be used if combined with the appropriate operators.

You can also add limits to an operator (for example, an integral) by first clicking the desired operator and then clicking the limit symbol. This method is faster than typing the commands directly.

The command liminf inserts the limit inferior with one placeholder.

The command limsup inserts the limit superior with one placeholder.

By typing oper in the Commands window, you can insert user-defined operators in LibreOffice Math, a feature useful for incorporating special characters into a formula. An example is oper %theta x. Using the oper command, you can also insert characters not in the default LibreOffice character set. oper can also be used in connection with limits; for example, oper %union from {i=1} to n x_{i}. In this example, the union symbol is indicated by the name union. However, this is not one of the predefined symbols. To define it, choose Tools - Symbols. select Special as the symbol set in the dialogue box that appears, then click the Edit button. In the next dialogue box, select Special as the symbol set again. Enter a meaningful name in the Symbol text box, for example, "union" and then click the union symbol in the set of symbols. Click Add and then OK. Click Close to close the Symbols dialogue box. You are now finished and can type the union symbol in the Commands window, by entering oper %union.

Limits can be arranged in ways other than centred above/below the operator. Use the options provided by LibreOffice Math for working with superscript and subscript indices. For example, type sum_a^b c in the Commands window to arrange the limits to the right of the sum symbol. If your limit entries contain longer expressions, you must put them in group brackets, for example, sum_{i=1}^{2*n} b. When formulae are imported from older versions this is done automatically. To change the spacing (gaps) between the characters choose Format - Spacing - Category - Indices or Format - Spacing - Category - Limits. Additional basic information about indices is given elsewhere in the Help.

When you type information manually in the Commands window, note that a number of operators require spaces for correct structure. This is especially true when your operators are supplied with values instead of placeholders, for example, lim a_{n}=a.