### Button Functions in Mathlets

In the 2-dimensional graphing applets, there are 4 buttons underneath the displayed graph:
• Zoom In causes the graph to enlarge by a factor of 2, with the center of the new graph region given by the coordinates of the next mouse click on the graph (so two clicks are needed, first on the button, then on the graph).
• Zoom Out causes the graph to reduce by a factor of 2, with the center of the new graph region given by the coordinates of the next mouse click on the graph (so two clicks are needed, first on the button, then on the graph).
• Mouse causes the display to show the coordinates of the mouse position, in coordinate units -- clicking this button again turns the display off.
• Bounds causes a pop-up window to appear, showing 6 text input fields and 4 buttons. The 6 text input fields are:
• xmin: the left (lower) endpoint of the x-axis
• xmax: the right (upper) endpoint of the x-axis
• Δx: the distance (in x-coordinate units) between hash marks on the x-axis
• ymin: the lower endpoint of the y-axis
• ymax: the upper endpoint of the y-axis
• Δy: the distance (in y-coordinate units) between hash marks on the y-axis
Each of these text input fields will accept any decimal number.
The buttons perform the following tasks:
• Square causes the axis settings for the graph to be changed so that the marked units (determined by delx and dely) are the same length on both axes, by increasing the number of units on one axis, as necessary, redrawing the graph and setting the text input fields to match (but not closing the pop-up window).
• Std causes the standard settings for the graph (xmin=-10.0, xmax=10.0, Δx=1.0, ymin=-10.0, ymax=10.0, Δy=1.0) to take effect, redrawing the graph and setting the text input fields to match (but not closing the pop-up window).
• OK causes the current settings of the values in the text fields to take effect, redrawing the graph and closing the pop-up window.
• Cancel closes the pop-up window with no further effect on the graph.
In the 3-dimensional graphing applets, there are 2 buttons underneath the displayed graph:
• Bounds -- as above, but 3 additional text input fields are available:
• zmin: the lower endpoint of the z-axis
• zmax: the upper endpoint of the z-axis
• Δz: the distance (in z-coordinate units) between hash marks on the z-axis
The buttons available in this pop-up window are a bit different, too:
• Square is not available.
• Apply causes the current settings of the values in the text fields to take effect (but not closing the pop-up window).
• View/Grid causes a pop-up window to appear, showing 4 text input fields and 5 buttons. The 4 text input fields are:
• a: (View Angle) specifies first viewing angle, measured counterclockwise in xy-plane, in degrees.
• b: (View Angle) specifies second viewing angle, measured down from z-axis, in degrees.
• xgrid: graph grid spacing in x direction
• ygrid: graph grid spacing in y direction
Each of these text input fields will accept any decimal number.
The buttons perform the following tasks:
• Enter View Point causes another pop-up window to appear, showing 3 text input fields and two buttons. The 3 text input fields are x, y, and z, the coordinates of a point in space. The OK button computes the view angles a and b (see above), enters them into the corresponding fields in the previous pop-up window, and closes this pop-up window -- the effect is that the graph is rotated so that it is shown as though seen from the point (x,y,z) in space. The Cancel button closes the pop-up window with no effect on the graph.
• Std causes the standard settings for the graph (a=45, b=45, xgrid=1.0, ygrid=1.0) to take effect, redrawing the graph and setting the text input fields to match (but not closing the pop-up window).
• Apply causes the current settings of the values in the text fields to take effect (but not closing the pop-up window).
• OK causes the current settings of the values in the text fields to take effect, redrawing the graph and closing the pop-up window.
• Cancel closes the pop-up window with no further effect on the graph.
There are a few applet-specific differences:
• In cylindrical coordinates, the grid values in the View/Grid pop-up window are specified as rgrid and θgrid
• In spherical coordinates, the grid values in the View/Grid pop-up window are specified as θgrid and φgrid
• In parametric surfaces, the grid values in the View/Grid pop-up window are specified as sgrid and tgrid
• In several 3-D applets (parametric paths; points, lines, and vectors; vector fields), the xgrid and ygrid fields are unnecessary, and are therefore not supported.
• In the 2-D applets with two separate graphs (Jacobians, integration by parts, and substitution 1 and 2), the second graph uses coordinates u and v instead of x and y, so the fields in the pop-up window brought up by the Bounds button for the second graph are marked by umin, umax, Δu, vmin, vmax, and Δv.
• In sequences and series, only 5 text input fields are available in the Bounds pop-up window: nmin (minimum value of n -- maximum value is nmin+100), Δn (distance between hash marks on the horizontal axis), ymin, ymax, and Δy.