FAQ

Q: FIX program does not work for a system with only one parameter.

A: BUNKI of current version cannot analyze bifurcation phenomena for a system with only one parameter. FIX and BF programs are tools to make a two-parameter bifurcation diagram, and therefore, they output an error when the calculation result is displayed since it needs two parameters in its calculation. In order to analyze bifurcation phenomena in such system you should add a dummy parameter to the system as the following example:

• dx[1]/dt = \$dummy\$*( f(x[1], x[2],...,x[n] ))
• dummy = 1.

Then FIX program works for the above system. However, even if you add a dummy parameter as the above system, it is actually difficult to make a two-parameter bifurcation diagram. Because the value of the dummy parameter may be changed in calculation of BF program, i.e., the system is different from the original system when the value of the dummy parameter is changed. Note that SE and PP programs work for a one-parameter system without adding a dummy parameter.

Q: There is no response from FIX program in its execution.

A: Newton method is implemented to FIX program. When a critical situation for numerical calculation occurs in spite of normal working of FIX program, it outputs a prescribed error message. If there is no message, it is thinkable that Newton method works abnormally. If there is no response from FIX program without any error message, you should stop FIX program by Ctrl + c in MATLAB command window. Subsequently, you check whether the set values of initial state and period in the configuration file of FIX program. As typical wrong configuration, set value of period is different from the period of target periodic solution. There is also no response from FIX program when a bifurcation parameter value closes to saddle-node bifurcation point. In the case, you try to make the step size of a bifurcation parameter smaller.

Q: There is no response from BF program in its execution.

• A: Newton method is also implemented to BF program. When a critical situation for numerical calculation occurs in spite of normal working of BF program, it outputs a prescribed error message. If there is no message, it is thinkable that Newton method works abnormally. If there is no response from FIX program without any error message, you should stop FIX program by Ctrl + c in MATLAB command window. This generally occurs when a bifurcation parameter value closes to saddle-node bifurcation point or a cusp point. In the case, you try to make the step size of a bifurcation parameter smaller.

Q: Bug-fix is not reflected although BUNKI program is updated.

A: An bug in BUNKI program is fixed, and the bug-fix version is released rapidly. Please frequently check whether the latest version of BUNKI is released, and it is recommended that your BUNKI is updated if the new version is released. If you update the program, you have to reconfigure PP, FIX, and BF programs after you delete configuration files under the following directory:

`"Project directory/save/".`

Before the delete, you had better export the configurations to xml-format files. Then you do not need input equations and configurations for PP, FIX, and BF programs again in new version of BUNKI. To export configuration files for SE, PP, FIX, and BF to XML-format files, please refer to the following links.

Q: Calculation of BF program does not automatically stop in its execution.

A: In order to stop calculation of BF program automatically, setting of the stop parameter for BF program is required. The stop parameter can be set in a configuration file for BF program. In the case without setting it, calculation of BF program can be terminated by clicking the stop button in the main panel at any time. Note that its calculation is automatically terminated in the following cases without setting the stop parameter:

• when current bifurcation parameters are at a cusp point
• when the program finds a bifurcation point of another solution
• when a numerical integration error occurs.

Q: How to visualize a bifurcation set.

A: Data of a bifurcation set is stored in the following directory

"Project directory/BF_data".

You can visualize the data by our plotting tool (BFP). The tool can be started up by making choice of "Program -> BFP" in the menu bar of the main panel. For more information, please refer to the users guide of BFP.

Last-modified: 2009-07-23 (Thu) 20:13:30 (3650d)