Features of the Ellipse Program
By default, ratio of a/b is set to 1.5. The user may choose to enter any number that is great than or equal to 1. After the user hits Return, an ellipse with the specified ratio will be drawn.
By default, number of iterations is set to 20. The user may choose to enter any integer that is greater than 0. After the user hits Return, the value is read.
By default, the starting position is set to (0,0) in the center of the ellipse. The user may choose to enter any integer coordinates ranging from (-150,-150) to (150,150). However, if the starting position is outside the ellipse, no trajectory will be drawn when Draw Button is pressed. An alternative way to input the starting position is to press the mouse in the ellipse where the user wants it to start.
By default, the velocity in horizontal direction(vx) is set to 0.8 and the velocity in vertical direction(vy) is set to 0.6. The user may choose to enter any value. The alternative way to input the velocity is to press the mouse and then drag it to the direction of the initial motion of the billiard.
By default, the unit speed of the billiard is set to medium. The user may change it by scrolling the scrollbar.
By default, the program is set to show both the trajectory and the phase diagram, no matter when the Draw Button is pressed or the phase window is clicked. The user may choose to show both trajectory and the phase diagram or only the phase diagram by checking the checkboxes.
When the Draw Button is pressed, the iteration will start. The label of button will be changed to Continue. By clicking on it, the user can continue the iteration. When any textfield value, checkboxes or speed is changed, the label will be reset to Draw.
When Erase Button is pressed, the trajectory drawn will be erased. Otherwise, when Draw Button is pressed, new trajectory will be drawn without erasing the old one.
The user may open the phase window by pressing the Open Phase Diagram Button. Then the label of the button will be changed to Close Phase Diagram. The user may choose to close the phase window by either pressing the Close Button on the phase diagram or on the main panel.
By default, the phase diagram shows phasediagram_horizontal. The user may choose to see phasediagram_tangent by clicking on the Go To Tangent Button.
The dots on the phase diagram will be erased when Clear Button is pressed.
When the user clicks the mouse on some area of the phasediagram_horizontal, the iteration will not start. This is normal, because he or she has clicked on the area where the starting position and the velocity vector are not possible to start the iterations.