### 3.5.10 The configuration file: widget_size cas_setup xcas_mode xyztrange

When you save changes to your configuration, this is stored in a configuration file, which will be .xcasrc in your home directory in Unix and xcas.rc in Windows. This file will have four functions – widget_size, cas_setup, xcas_mode and xyztrange – which determine the configuration and which are evaluated when Xcas starts.

The widget_size function has between 1 and 12 arguments. The arguments (in order) are:

- The first argument is a postive integer specifying the font size. Optionally, this can be a bracketed list whose first number indicates the font and the second the font size.
- The second and third arguments are horizontal and vertical distances in pixels from the upper left hand corner of the screen. They specify where the upper left corner of the Xcas window is when it opens.
- The fourth and fifth arguments specify the width and height of the Xcas window when it opens.
- The sixth argument is either 0 or 1; a 1 indicates that the on-screen keyboard should be open when Xcas starts, a 0 indicates that the keyboard should be hidden.
- The seventh argument is either 0 or 1; a 1 indicates that the browser should be automatically opened to display help for the selected command in the menu or index, a 0 indicates that the browser should not be automatically opened.
- The eighth argument is either 0 or 1; a 1 indicates that Xcas should open with the message window, a 0 indicates that Xcas should open without the message window.
- The ninth argument is currently not used.
- The tenth argument is a string with the name of the browser to use to read the help pages. A value of "builtin" means that Xcas should use a small browser built into Xcas.
- The eleventh argument indicates what level Xcas should start at; a 0 means command line, a 1 means program editor, a 2 means spreadsheet, and a 3 means a 2-d geometry screen.
- The twelfth argument is a string with the name of a program for postscript previews; for example, "gv".

The cas_setup function has nine arguments. The arguments (in order) are:

- approx. A 1 means Xcas works in approximate mode, a 0 means numeric mode.
- complex_var. A 1 means work with complex variables, a 0 means real variables.
- complex. A 1 means work with in complex mode, a 0 means real mode.
- radian. A 1 means work in radians, a 0 means work in degrees.
- display_format. A 0 means use the standard format to display numbers, a 1 means use scientific format, a 2 means use engineering format, and a 3 means use floating hexademical format (which is standardized with a non-zero first digit).
- epsilon. This is the value of epsilon used by Xcas.
- Digits. This is the number of digits to use to display a float.
- tasks. This will be used in the future for parallelism.
- increasing_power. This is 0 to display polynomials in increasing power, 1 to display polynomials in decreasing powers.

The xcas_mode function has one argument; a 0 to work in Xcas mode, a 1 to work in Maple mode, a 2 to work in MuPAD mode, and a 3 to work in TI89 mode.

The xyztrange function inserts or removes the axes of a geometric screen; it has 15 parameters, which are the parameters which can be set with the graphics configuration screen (see section 3.5.8).
Input:

xyztrange (-5.5, -5.2, -10.10, -1.6, -5.5, -1.2384,2,1,0,1)

(or enter the information in the configuration screen) will result in a visible graphics window of [-5,5] by [-1.2384,2]. Note that the visible window is not the same as the calculation window; if the calculation window is larger than the visible window, then you can scroll to bring other parts of the calculation window into view.