Colors

The use of this tool is illustrated in the Cartesian Plane.

The configuration panel of the tool COLORS has only four lines:

BACKGROUND=white
NET=lightGray
AXES=gray
TEXT=darkGray

where the colour names white, lightGray etc... may be substituted by any of the predefined colours or by hexadecimal expressions that specify a colour.

The predefined colours are: balck, darkGray, gray, lightGray, white, pink, red, orange, yellow, green, cyan, blue and magenta. The spanish names of these colours can also be used (see the table at the end of the page).

A hexadecimal expression is a string which contains only hexadecimal digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f . In order to define a colour by means of a hexadecimal expression it is necessary to forme a string with six hexadecimal digits. They are interpreted in pairs. The first two represent the quantity of red, the next two represent the quantity of green and the last two represent the quantity of blue that the colour contains. For example:

aa44ff

represents a colour with aa of red, 44 of green and ff of blue. In decimal numbers, aa=10*16+10=170, 44=4*16+4=68 and ff=15*16+15=255. In general, to convert a two digit hexadecimal number to decimal form, one has to multiply the value of the first digit by 16 and add the value of the second. It is not necessary to make this conversion, one can easily learn to undestand hexadecimal expressions without having to translate them. For most purposes, it is enough to use the 16 combinations: 00, 11, ..., ff to represent the quantities of the primary colours that form a certain colour. With these combinations it is possible to represent all the colours the user may need, unless his or her perception of colour is extremely refined.

The colours of all Descates graphs are defined adding a statement of the form colour=yellow to the configuration line, separated by : from the other statements. Of course yellow may be substituted by any of the predefined colours or by a hexadecimal expression.

It is recommended that the reader practices with the following example to define several colours for the BACKGROUND, the NET, the AXES, the TEXT and the graph of the equation y=a*x^2+b*x+c.

The reader should remember that to make these changes on the configuration, he or she must click  the config button, then select the tool (in this case COLORS or EQUATIONS), make the changes and click the test button.

This table shows the hexadecimal expressions of the predefined colours and their names in spanish:

Introduction  Appetizer  Examples  Documentation  Applications  Work plan

	Ministerio de Educación, Cultura y Deporte. Aņo 2000