How do i get a direction field plot?

Hello, I need to plot a direction field for this differential equation

dP/dt=0.0015*P*(1-(P/6000))

how would I do it?

Thank you for helping.

Answer 1

[Sam Chak]

Hi @Tuân Nguyen

Because there are two equilibrium points and , I think it should look like this.

[T, P] = meshgrid(0:6e3/14:6e3, 0:6e3/14:6e3);
S = 0.0015*P.*(1 - (P/6000));
L = sqrt(1 + S.^2);
U = 1./L;
V = S./L;
quiver(T, P, U, V, 0.5)
axis square
xlabel('t')
ylabel('P(t)')

[Tuân Nguyen]

thank you so much, appreciate it!

[Tuân Nguyen]

Hi @Sam Chak

As the code that you replied me with, I wonder how can I extend the interval of P(t) to 8000?

thank you!

[Sam Chak]

Hi @Tuân Nguyen

In this line, you can change the range of P.

[T, P] = meshgrid(0:(6000-0)/14:6000, 0:(8000-0)/14:8000);

Here is the syntax:

x_start:h:x_end

where h is the spacing between the points.

(8000-0)/14

will generate 15 points between 0 to 8000 in P