Create a Vector fields

I trying to create a vector field of a diferentials equation system, I write a code in matlab app designer but I not sure how to do it. I write this code but I can't run it, this is the code:

P = 50;

Q = 60;

a = app.a.Value;

b = app.b.Value;

N = 15;

xmin = 0;

xmax = 10;

ymin = 0;

ymax = 10;

[x,y] = meshgrid (xmin: (xmax-xmin)/N:xmax,ymin:(ymax-ymin)/N:ymax);

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

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

% in the line before i have this error Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

quiver (app.Axes,x,y,dx,dy);

Someone knows if this code is correct for getting a vector field or knows how to solve the error. Thanks

Answer 1

[KALYAN ACHARJYA]

"% in the line before i have this error Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters"

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

May be because of Extra Bracket..?