> я хочу получить квадрат с дырой внутри от круга
> i want to create a square with a hole inside from the circle
Since your surfaces are flat and centered on (0,0) you just need to use the radius of the circle to subtract the circle from the square surface.
[x1,y1] = meshgrid(-2:0.1:2,-2:0.1:2);
circIdx = hypot(x1,y1) < radius;
> так же если возможно объясните как получить поверхность круга в виде нормальной декартовой сетки, а не в виде полярной
> also, if possible, explain how to get the surface of a circle as a normal Cartesian grid, not polar
The circular surface in your question is already in Cartesian coordinates. pol2cart converts polar coordinates to Cartesian.
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