Copying the Demo Files.

The commands listed in Table 12.1 will copy the demo files to your work directory.

Table 12.1: Copying the demo cusp files.

Unix-COMMAND	ACTION
auto	start the AUTO-07p Command Line User Interface
AUTO -COMMAND	ACTION
cd	go to main directory (or other directory).
! mkdir cusp	create an empty work directory. Note: the '!' is used to signify a command which is sent to the shell.
cd cusp	change to the work directory.
demo('cusp')	copy the demo files to the work directory.

Typing ls reveals the existence of 5 files:

1. cusp.f90 : This file contains the differential equations and the initial values. If you inspect it, you will see that only two routines are used. The subroutine FUNC specifies the actual differential equation. The routine STPNT gives AUTO the initial values of PAR(1)$=\lambda$ and PAR(2)$=\mu$, which are $1.0$ and $0.0$, and the initial value of $x$, which is 0. For your own models you would generally copy another equation file and then only change the pieces that actually define the equation.

2. c.cusp : The initial computational constants are stored in this file. Most importantly, you see that the dimension of the problem (NDIM) is set to 1, and the problem type IPS is set to 1 to specify continuation of a stationary solution. The constants given by ICP specify the parameters that are used for the continuation. In this case these are 2 for $\mu$ and 1 for $\lambda$. Since initially we only really continue in one parameter ($\mu$), the second parameter $\lambda$ is overspecified. Another important constant is the initial step size DS: as it is positive, we initally continue in the positive $\mu$ direction.

3. c.cusp.1 : A copy of c.cusp, for convenience.

4. cusp.auto : A script with Python CLUI commands that steer the calculation.

5. plaut04.rc : A file that contains default settings for the 3-dimensional plotting tool PLAUT04.