How to genrate inward normals to a circle having 20 points ?

I have a circle having 20 points in it's periphery.

I amd doing this

R = 1;          %Radius of  1
n = 20;
UV1 = zeros(n,3); 
j = 1;
for angle = 0:-pi/n:-pi;

   P1 =[R*cos(angle) R*sin(angle) 0];
   P2 =[R*cos(angle-pi/n) R*sin(angle-pi/n) 0];
   P3 = [0 0 1]; 

   u = cross(P1-P2,P3);
   u1 = (u/norm(u));

   UV1(j,1:3) = u1;
   j = j+1;

    c = u1 + P1;
    quiver3(P1(1), P1(2), P1(3), c(1), c(2), c(3)); 

%   pts = [P2; P1;];
%   line(pts(:,1), pts(:,2), pts(:,3))    

    hold on;

end
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it's pointing outwards

I want to generate normals at every point on the ciecle pointing inwards

Please help me

[John D'Errico]

What direction does a normal to a circle point?

An inward pointing normal lies on a line that ALWAYS passes through the center of the circle.

So given any point on the periphery, it would seem you know two points on the line for the corresponding normal.