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Memory Objects

Internally, dstool stores data as a memory object. There are currently six types of memory objects: trajectory data, multiple trajectory objects, fixed point data, continuation data, parameter data, and selected point data. Parameter data differs from selected point data in that parameter data is displayed in those view windows whose coordinate axes are all parameters; selected point data is not displayed in those view windows, but is displayed in all others. Each memory object consists of a header and a body. The header contains information which is relevant to all elements of the memory object; the body consists of a list of points.

When memory objects are stored, the header information is stored first, followed by the body. The following is an example of a memory object for trajectory data:

# New_Traj
# Objects 1
# Double_Params 3 : 10 28 2.66666666 
# Integer_Params 3 : 0 0 1 
# Doubles= 4 Integers= 0
# New_Obj:  500 Points
3.33333333333 5.11111111111 0.1            0.0 
3.54567210552 6.01044205838 0.285917212245 0.01 
... (total of 500 points) ...
5.07133527463 10.2650449956 1.57313739354  5.00

A block of data such as the above will begin with one of the six strings New_Traj, New_Mult, New_Fxpt, New_Cont, New_Param, New_Sel_Pt which identify the type of data which follows. The above data defines a trajectory for a vector field which has three parameters and four phase space variables--three spatial variables plus time. The parameters are stored in the header whereas the phase space variables are stored in the body. In the above data, three integer parameters in the header are used to indicate the symbol type, size, and color of the trajectory.

Note that in dstool the independent variable (often time) is given full status as a member of phase space. Consequently, the ``dstool dimension'' of phase space may be greater than the commonly accepted dimension. For example, vector fields which are time independent have the same ``dstool dimension'' as vector fields which are time-dependent. This has been done so that dstool may handle autonomous and non-autonomous systems in a uniform way. It should not be a source of confusion unless you intend to load data into dstool which has been written by an external application. See section 1.2 below.


next up previous contents
Next: Auxillary Function Values Up: dstool Format Previous: Configuration   Contents
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1998-11-02