next up previous contents
Next: Bibliography Up: A Torus Diffeomorphism Previous: More on Manifolds   Contents


Saving and Loading Data

The Kim-Ostlund torus map undergoes many bifurcations as the parameters are changed [4], [5], [6]. In investigating the behavior of a complicated dynamical system, researchers often find it convenient to save system information associated with interesting dynamics. In this section we will save information about the torus map to a file and then retrieve the information.

If necessary, open the Selected Point panel using \framebox{MENU} on the Settings menu button of the dstool command window. Clear the 2-D Image window with \framebox{Control-MIDDLE}. Then change the value of wx to 0.5 and change the value of wy to 0.8. Generate a phase portrait for these parameter values. (See figure [*] .)

Suppose that you wish to save this phase portrait. With dstool you have several options. The first option (the default) is to save only the information about the phase portrait. This includes the name of the dynamical system being studied, the parameter values, values of some tolerances used in numerical computations, and a few lines worth of other information. The default option does not save any data points. The advantage of this option is that it does not require the storage of the large amount of data which actually comprise the phase portrait - yet the phase portrait may be fully reconstructed.

Using \framebox{MENU} on the File menu button of the command window, select the menu entry Save... to open the Save panel. Edit the Directory: and Filename: fields appropriately to set the name of the data file in some directory where you have write access. Options specify exactly which data is saved. Use \framebox{SELECT} to toggle these choices on or off. Choices are boxed within darker rectangles when they have been selected. In this case, \framebox{SELECT} the option Current Settings. Now click \framebox{SELECT} on the Save button at the bottom of the panel to actually save the data.

To reload this data at some later point, open the Load panel by selecting with \framebox{MENU} the Load... menu entry button of the File menu button on the command window. Edit the Directory: and Filename: fields to the same choices you made before. Maintain the option dstool Format right now. ( The dstool Reference Manual describes how to import unformatted data into a dstool memory object. ) Clicking \framebox{SELECT} on the Load button will then restore the dstool settings.

We remark that saving and loading trajectory data is significantly slower than merely saving the Current Settings values. The length of time needed to save or load data depends on the number of data points, the dimension of the phase space, and the particular machine running dstool.


next up previous contents
Next: Bibliography Up: A Torus Diffeomorphism Previous: More on Manifolds   Contents
root
1998-11-02