Writing exponent in pplane for Matlab

I'm trying to use the pplane code to generate a phase portrait for

dn/dt=n^(2/3)*(1−n)−en

but the graph will not acknowledge 2/3 as a full exponent.I keep getting things that look like this when I type n^(2/3):

Or when I type n^2/3 it'll make a graph using (n^2)/3.

How can I fix this? Or rewrite the equation in pplane to graph the correct form of the equation?

Thank you

Answer 1

[John D'Errico]

pplane is not part of MATLAB, so it must be a package from the file exchange, or some other source. You might want to contact the author with questions.

You raise a number to a fractional power like this:

n^(2/3)

Why? Exponentiation has a higher order of precedence than division. So when you wrote n^2/3, MATLAB sees n^2, and recgnizes that exponentation comes first in the list. So it squares n, and THEN divides the result by 3.

Since you want MATLAB to raise it to the (2/3) power, just use parens as I show.

[Holli Sharples]

yes, unfortunately I did try that the first time and gave me this for the graph:

It only put the first paranthesis in the exponent position and left the rest as scalars.