Error using quiver The size of Y must match the size of U or the number of rows of U.

i am trying to create a vector field with app designer with the function quiver but i have an error 'Error using quiver

The size of Y must match the size of U or the number of rows of U.'

a = app.a.Value;

b = app.b.Value;

x1=0;

x2=2;

y1=0;

y2=2;

N = 20;

x = linspace(x1,x2,N);

y = linspace(y1,y2,N);

[X,Y]= meshgrid(x,y);

m = a.*y/b.*x;

S = atan (m);

U = cos (S);

V = sin (S);

quiver (app.Axes, X,Y,U,V);

Answer 1

[KALYAN ACHARJYA]

Refer the MATLAB Docs, where U and V must be 2D as same sizes of X and Y. Please add the following line, this may allow to avoid the error

[U,V]=meshgrid(U,V);

[KALYAN ACHARJYA]

I have tried with non App case (Assigning the value a and b directly)

 a = 2;
 b= 3;
 x1=0;
 x2=2;
 y1=0;
 y2=2;
 N = 20;
 x = linspace(x1,x2,N);
 y = linspace(y1,y2,N);
 [X,Y]= meshgrid(x,y);
  m = a.*y/b.*x;
  S = atan (m);
  U = cos (S);
  V = sin (S);
  [U,V]=meshgrid(U,V);
  quiver (X,Y,U,V);
  

[Alvaro Mª Zumalacarregui Delgado]

Thank you very much!! i get it

Answer 2

[Alvaro Mª Zumalacarregui Delgado]

I have the same error but with other code, I only change the "m" value and Matlab sends me the same error:

P = 50;

Q = 60;

a = app.a.Value;

b = app.b.Value;

x1=0;

x2=2;

y1=0;

y2=2;

N = 20;

x = linspace(x1,x2,N);

y = linspace(y1,y2,N);

[X,Y]= meshgrid(x,y);

m = (P-a*y)/(Q-b*x);

S = atan (m);

U = -cos (S);

V = -sin (S);

[U,V]=meshgrid(U,V);

quiver (app.Axes, X,Y,U,V);

[KALYAN ACHARJYA]

m = (P-a*y)./(Q-b*x);
%..........^

[Alvaro Mª Zumalacarregui Delgado]

Thank you so much! you can't imagine how you help me with that!