In Quiver Function Error: " index must be a positive integer or logical."

Hey,

I get the error

??? Attempted to access quiver(2.76604,2.17365,-0.123257,0.81116); index must be a positive integer or logical.

and can't imagine why, because if I type quiver(2.76604,2.17365,-0.123257,0.81116) in the Command Window it works well.

Here is the Code:

      for k=1:n
          for l=1:n
              if E(k,l) >= 1
                  x1=2+cos(2*pi/n*k); x2=2+cos(2*pi/n*l); y1=2+sin(2*pi/n*k); y2=2+sin(2*pi/n*l);
                  u=y1-x1; v=y2-x2;
                  quiver(x1,x2,u,v);%,'Color',color,'LineWidth',2);
              end
          end
      end

with n=length(E) and E(i,j) = 1 if there excists an arrow between i and j

Thank You Daniel

[David Sanchez]

I run the following code and it worked for me:

n=3;      
for k=1:n
          for l=1:n
                  x1=2+cos(2*pi/n*k); 
                  x2=2+cos(2*pi/n*l); 
                  y1=2+sin(2*pi/n*k); 
                  y2=2+sin(2*pi/n*l);
                  u=y1-x1; 
                  v=y2-x2;
                  quiver(x1,x2,u,v);
          end
end

Is the code you presented the one that yields the error?

[Daniel]

Hmm this is weird because if I run exactly your modification of the code I get the error:

??? Attempted to access quiver(1.5,1.5,1.36603,1.36603); index must be a positive integer or logical.

Error in paintgraph at 23

quiver(x1,x2,u,v);

I can't imagine why. Yes the code I presented yields the error.

[Daniel]

Got the solution. I accidantly set quiver=1 earlier.

Thank you very much.

Answer 1

[Sajid Khan]

use clear all before executing your code.