Handling auxiliary functions in the construction of the odefile

If complicated expressions arise several times in the definition of a dynamical system then is often useful to give them a name. A simple example is the following system (a catalytic oscillator, (60):

$\displaystyle \left\{\begin{array}{rcl}
\dot x & = & 2q_1z^2 -2q_5x^2 -q_3xy \\
\dot y & = & q_2z -q_6y -q_3xy\\
\dot s & = & q_4z -kq_4s
\end{array}\right.$     (31)

where $z=1 -x -y -s$. When SysGUI.new is used to create the odefile of the system then is not necessary to ``expand" the auxiliary function for $z.$ The system can be introduced as

z=1-x-y-s
x'=2*q1*z^2-2*q5*x^2-q3*x*y
y'=q2*z-q6*y-q3*x*y
z'=q4*z-k*q4*s

We note that the definition of the auxiliary functions must precede the definiton of the right hand sides.

The corresponding odefile is cataloscill.m in the directory Testruns/TestSystems.