MATLAB: Creating a rectangle image by using an user defined function

Question

I am trying to create a rectangle image as you see but I have a problem with the equation part of the rectangle. Can anyone help to fix this up? Thank you in advance.

function outimg = RectIm(x, y)
SizeX = 256;
SizeY = 256;
[C, R] = meshgrid(1:SizeX, 1:SizeY);
centerX = 128;
centerY = 128;
rectangle = (R - centerY/2)*(C - centerX/2) <= x*y ;
outimg=image(rectangle);
colormap([0 0 0.4; 1 1 1]);
end

Answer 1

rectangle = (R - centerY/2).*(C - centerX/2) <= x*y ;

This is not going to define a rectangle, though: it is going to define a hyperbola.

Perhaps you want

rectangle = abs(R - centerY/2) <= y/2 & abs(C - centerX/2) <= x/2 ;