Can anyone explain this step:? Contour function

Considering :

X = 80 x 800;

Y = 80 x 800

c = 80 x 800

Why the code below results in a 2 x 81 matrix (c5)?

c5 = contour(X,Y,c,[0.5 0.5]);

Answer 1

[KSSV]

[X,Y,Z] = peaks(50) ; 
c = contour(X,Y,Z) ;
hold on
plot(c(1,:),c(2,:),'*r')
axis([-3 3 -3 3])

It gives you the (x,y) coordinates of the contour lines.