### 2.3.3 Help index

If you click on the ? button on the status line you will get the help index. You can also get the help index with the menu item Help▸Index.

> Figure 2.3: Help index in Xcas

The help index, shown in Figure 2.3, is a list of the giac function and variable names. You can scroll through the help index items and click on the word that you want. There is also a line in the help index window that you can use to search the index; you can enter some text and be taken to the part of the index with the words that begin with that text. The ? button next to this search line will open the HTML help window.

If you select a function or variable name, a list of related words (names of functions or variables) and a list of synonymous words will appear in regions to the right. Below the search line, there will be an area which will have a brief description of the chosen term as well as how to call it. If the term is a command name, the calling sequence will be given as the command name with the arguments within parentheses separated by commas. Any optional arguments will be shown within brackets. In the window shown in Figure 2.3, the first argument to plotfunc is an expression, representing the function to be graphed. There is an optional second argument, which is either a variable name (which defaults to x) or a vector of variable names for multivariable functions. Finally, there is an optional third argument which can be used to specify a color for the graph.

Below the brief description will be some entry fields that use to enter the arguments. If you fill them out and press the enter key, the command with the arguments filled out will be put on the command line.

Below the entry fields for the arguments will be a list of examples of the command being used. If you click on one of these examples, it will be put on the command line.

A more thorough description of the function and its arguments is available with the Details button at the top of the help index, which will open the relevant part of the manual in your browser. Alternatively, if you click on the ? button next to the search line, you will be taken to the HTML help window.

You can also open the help index in the following ways:

- You can press the tab key while typing in the Xcas command box. If you have entered part of a command name, you will be at the part of the index with words that begin with the text that you entered.
- You can select a command from one of the menus. If Auto index help is chosen (see Section 2.5.9), then the help index will open with the command chosen.