My professor wants us to use the following plotter to plot phase portraits for systems of ODEs but for whatever reason I do not know, neither my professor, nor myself could get this to work on my laptop:
http://comp.uark.edu/~aeb019/pplane.html
So instead, I am trying to use Matlab 2017a (which I personally believe is a better idea and overall better for me).
my first system of (nonlinear) ODEs is as follows: $$x' = 4x - x^3$$ $$y' = y^2 - 3y$$
my second system of (nonlinear) ODEs is as follows: $$x' = 2x -xy$$ $$y' = x^3 - (1/2)y$$
In class we sketched the phase portrait for the second system of nonlinear ODEs by linearizaton via the Jacobian matrix. I can solve these but I am struggling to plot these in Matlab (and haven't made any progress unfortunately)and would absolutely be grateful for some help. Thanks in advance!
From PPLANE dfield and pplane, the java versions