# Direction field and slope field- quiver

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Anand Ra on 26 Nov 2021
Commented: Anand Ra on 30 Nov 2021
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.
##### 2 CommentsShowHide 1 older comment
Anand Ra on 29 Nov 2021
Hello Shivam, thanks for responding.
Its suppose to be N ( r=N). My bad, sorry for the typo.

Shivam Singh on 29 Nov 2021
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.
##### 1 CommentShowHide None
Anand Ra on 30 Nov 2021
Thank you @Shivam Singh