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OOMMF eXtensible Solver Interactive Interface: Oxsii

Oxsii Screen Shot

The application Oxsii is the graphical, interactive user interface to the Oxs micromagnetic computation engine. Within the OOMMF architecture, Oxsii is both a server and a client application. Oxsii is a client of data table display and storage applications, and vector field display and storage applications. Oxsii is the server of a solver control service for which the only client is mmLaunch. It is through this service that mmLaunch provides a user interface window (shown above) on behalf of Oxsii.

A micromagnetic problem is communicated to Oxsii via a MIF 2.1 file, which defines a collection of Oxs_Ext objects that comprise the problem model. The problem description includes a segmentation of the lifetime of the simulation into stages. Stages mark discontinuous changes in model attributes, such as applied fields, and also serve to mark coarse grain simulation progress. Oxsii provides controls to advance the simulation, stopping between iterations, between stages, or only when the run is complete. Throughout the simulation, the user may save and display intermediate results, either interactively or via scheduling based on iteration and stage counts.

Oxsii may be started either by selecting the Oxsii button on mmLaunch, or from the command line via

tclsh oommf.tcl oxsii [standard options] [-parameters params] \
   [-pause <0|1>] [-nice <0|1>] [-exitondone <0|1>] [miffile]
-parameters params
Sets MIF 2.1 format file parameters. The params argument should be a list with an even number of arguments, corresponding to name + value pairs. This list must be quoted so it is presented to Oxsii as a single item on the command line. The quoting mechanism is shell/operating system specific. Refer to your system documentation for details.
-nice <0|1>
If enabled (i.e., 1), then the program will drop its scheduling priority after startup. The default is 1, i.e., to yield scheduling priority to other applications.
-pause <0|1>
If enabled (i.e., 1), then the program automatically pauses after loading the specified miffile. The default is 0, i.e., to automatically move into ``Run'' mode once the problem is loaded. This switch has no effect if miffile is not specified.
-exitondone <0|1>
Whether to exit after solution of the problem is complete. Default is to simply await the interactive selection of another problem to be solved.
Load and solve the problem found in miffile, which must be in the MIF 2.1 format. Optional.
All the above switches are optional.

Since Oxsii does not present any user interface window of its own, it depends on mmLaunch to provide an interface on its behalf. The entry for an instance of Oxsii in the Threads column of any running copy of mmLaunch has a checkbutton next to it. This button toggles the presence of a user interface window through which the user may control that instance of Oxsii.

Unlike mmSolve2D, Oxsii loads problem specifications directly from disk (via the File|Load... menu selection), rather than through mmProbEd or FileSource. Also, input files for Oxsii must be in the MIF 2.1 format, as opposed to the older MIF 1.1 format used by the 2D solver. There are sample MIF 2.1 files in the directory oommf/app/oxs/examples. The command line tool mifconvert can be used as an aid for converting MIF 1.1 files to the MIF 2.1 format. MIF files may be edited with any plain text editor.

Once a problem has been loaded, the scroll box under the Output heading will fill with a list of available outputs. The contents of this list will depend upon the Oxs_Ext objects specified in the input MIF file. Refer to the documentation for those objects for specific details. To send output from Oxsii to another OOMMF application, highlight the desired selection under the Output heading, make the corresponding selection under the Destination heading, and then specify the output timing under the Schedule heading. Outputs may be scheduled by the step or stage, and may be sent out interactively by pressing the Send button. The initial output configuration is set by Destination and Schedule commands in the input MIF file.

Outputs fall under two general categories: scalar (single-valued) outputs and vector field outputs. The scalar outputs are grouped together as the DataTable entry in the Output scroll box. Scalar outputs include such items as total and component energies, average magnetization, stage and iteration counts, max torque values. When the DataTable entry is selected, the Destination box will list all OOMMF applications accepting datatable-style input, i.e., all currently running mmDataTable, mmGraph, and mmArchive processes.

The vector field outputs include pointwise magnetization, various total and partial magnetic fields, and torques. Unlike the scalar outputs, the vector field outputs are listed individually in the Output scroll box. Allowed destinations for vector field output are running instances of mmDisp and mmArchive. Caution is advised when scheduling vector field output, especially with large problems, because the output may run many megabytes.

The File menu button holds 5 entries: Load, Show Console, Close Interface, Clear Schedule and Exit Oxsii. File|Load... launches a dialog box that allows the user to select an input MIF problem description file. File|Show Console brings up a Tcl shell console running off the Oxsii interface Tcl interpreter. This console is intended primary for debugging purposes. In particular, output from MIF Report commands may be viewed here. File|Close Interface will remove the interface window from the display, but leaves the solver running. This effect may also be obtained by deselecting the Oxsii interface button in the Threads list in mmLaunch. File|Clear Schedule will disable all currently active output schedules, exactly as if the user clicked through the interactive schedule interface one output and destination at a time and disabled each schedule-enabling checkbutton. The final entry, File|Exit Oxsii, terminates the Oxsii solver and closes the interface window.

The Help menu provides the usual help facilities.

The row of buttons immediately below the menu bar provides simulation progress control. These buttons become active once a problem has been loaded. The first button, Reload, re-reads the most recent problem MIF input file, re-initializes the solver, and pauses. Reset is similar, except the file is not re-read. The remaining four buttons, Run, Relax, Step and Pause place the solver into one of four run-states. In the Pause state, the solver sits idle awaiting further instructions. If Step is selected, then the solver will move forward one iteration and then Pause. In Relax mode, the solver takes at least one step, and then runs until it reaches a stage boundary, at which point the solver is paused. In Run mode, the solver runs until the end of the problem is reached. Interactive output is available in all modes; the scheduled outputs occur appropriately as the step and stage counts advance.

Directly below the progress control buttons are two display lines, showing the name of the input MIF file and the current run-state. Below the run-state Status line is the stage display and control bar. The simulation stage may be changed at any time by dragging the scroll bar or by typing the desired stage number into the text display box to the left of the scroll bar. Valid stage numbers are integers from 0 to N - 1, where N is the number of stages specified by the MIF input file.

The simulation model construction is governed by the Specify blocks in the input MIF file. Therefore, all aspects of the simulation are determined by the specified Oxs_Ext classes. Refer to the appropriate Oxs_Ext class documentation for simulation and computational details.

Known Bugs
A bug in the network traffic handling code of Tcl on Windows 9X systems can sometimes interfere with communications between the control interface of Oxsii and the actual computation engine. If Oxsii is sending out data to two or more data display services every iteration, the network traffic from that data can ``crowd out'' the receipt of control messages from the control interface. You may observe this as a long delay between the time you click the Pause button and the time the solver stops iterating. This bug first appeared in Tcl release 8.0.3, and remained through Tcl release 8.1.1. It is fixed in Tcl releases 8.2 and later, which we recommend for OOMMF users on Windows 9X systems. Other platforms do not have this problem.

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OOMMF Documentation Team
October 30, 2002