# Aðgerðir

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.

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Open the context menu in the Commands window - choose Operators

Choose View - Elements; then on the Elements pane select Operators from the listbox.

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

Takmörk

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

Summun

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

Vara

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

Hjámargfeldi

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

Efri og neðri mörk

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 centered above/below the summation character.

Heildi

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

Tvöfalt heildi

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

Þrefalt heildi

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

Neðri mörk

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

Ferilheildi

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

Tvöfalt ferilheildi

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

Þrefalt ferilheildi

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

Efri mörk

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 dialog that appears, then click the Edit button. In the next dialog, 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 dialog. 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 centered above/below the operator. Use the options provided by LibreOffice Math for working with superscript and subscript indexes. 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 formulas are imported from older versions this is done automatically. To change the spacing (gaps) between the characters choose Format - Spacing - Category - Indexes or Format - Spacing - Category - Limits. Additional basic information about indexes 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.