Space

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

The configuration panel of the tool SPACE must have these three lines:

scale=40:incr=10:min=10
Ox=0:incr=20
Oy=0:incr=20

which define the three basic space parameters: scale, Ox and Oy.

scale represents the number of pixels contained in a unit segmnent. For example, scale=40 means that there are exactly 40 pixels in a unit segment or between two consecutive lines of the underlying NET.

Ox represents the horizontal displacement, in pixeles, of the origin with respect to the center of the applet canvas where the graphs are drawn. For positive values of Ox the origin is located to the right of the applet's center while for negative values of Ox, the applet lies to the left of the applet's center .

Oy represents the vertical displacement, in pixeles, of the origin with respect to the center of the applet canvas where the graphs are drawn. For positive values of Oy the origin is located above the applet's center while for negative values of Oy the applet lies below the applet's center. This convention is the oposite of the usual math convention, but it is the usual one in programming languages. However the direction of the coordinate axes agrees with the usual mathematical convention, that is the points above the x axis have positive ordinate (y-coordinate) while the points below the x axis have negative ordinate (y-coordinate). In other words, only the location of the origin with respect to the center of the applet follows the programming language convention, all the rest agrees with the usual mathematical convention.

For every parameter there are four related numbers that determine its properties: min, max, incr and decimals.

Let v be the name of a parameter. Then:

incr  is the amount v is changes with every click on the arrows of its spinner control.
min    is the minimum value allowed for v.
max    is the maximum value allowed for v.
decimals is the number of digits, after the decimal point, used to represent v.

The lines on the configuration panel of SPACE must start by assigning a number to one of the space parameters scale, Ox or Oy. The rest of the line may have statements of value assignment to the related numbers, separated from each other by  :  .  If one of these lines is deleted the applet will not show the corresponmding spinner and text field and the value of the corresponding parameter will be fixed as its default value. The default values of the SPACE parameters and their related numbers are:

scale=32:incr=8:min=8:max=+infinity:decimals=2
Ox=0:incr=0.1:min=-infinity:max=+infinity:decimals=2
Oy=0:incr=0.1:min=-infinity:max=+infinity:decimals=2

In order to assign the values -infinity to min or +infinity to max it suffices to eliminate the statement which assigns values to min and max so the default values are adopted. If the user wants a certain parameter v to have a fixed value he or she must assign the same value to v, min and max.

The reader is invited to verify the values assigned in the following applet to the SPACE parameters by taking each one to its lower and upper limit and trying to assign values outside these limits. Try also to make several changes on the configuration values and to verify their meanings.

Introduction  Appetizer  Examples  Documentation  Applications  Work plan

	Ministerio de Educación, Cultura y Deporte. Aņo 2000