Direction field and slope field- quiver

Looking for some help to generate slope field for the below differential equation

% dN/dt = (b − a ln(N))N 

[N,t]=meshgrid(0:1:6,0:1:10);

%Case 1: b<a
b=10;
a=20;
dN=(b - a.*log(N)).*N;
dt=1;
dNu=dN./sqrt(dN.^2+dt.^2);
dtu=dt./sqrt(dN.^2+dt.^2);
quiver(N,t,dtu,dNu)

Note sure how to fix the above. Any help would be appreictaed. Thank you.

[Shivam Singh]

Hello Anand,

In the differential equation provided, dr/dt = (b − a ln(N))N, what is the "N"? Is it a variable different from "r" or the same?

[Anand Ra]

@Shivam Singh

Hello Shivam, thanks for responding.

Its suppose to be N ( r=N). My bad, sorry for the typo.

Answer 1

[Shivam Singh]

Hello Anand,

“quiver (X, Y, U, V)” plots arrows with directional components U and V at the Cartesian coordinates specified by X and Y. So, if you have a function Z = f(X, Y) with two independent variables X and Y, then you need two directional components, U and V as U = dZ/dX and V = dZ/dY to create a slope plot or direction plot.

Currently your code has only one independent variable 't' and a single directional component dN/dt.

For more information, you can explore “quiver” function.

[Anand Ra]

Thank you @Shivam Singh