Drawing a circle of ones by using a pre-defined grid with pcolor

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Sahin Kurekci 2019-9-14

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https://ww2.mathworks.cn/matlabcentral/answers/480369-drawing-a-circle-of-ones-by-using-a-pre-defined-grid-with-pcolor

评论： Sahin Kurekci 2019-9-14

采纳的回答： darova

在 MATLAB Online 中打开

I have the following grid in the beginning of my code:

a = 25, % This will be the radius of the circle
r = linspace(0,sqrt(2)*2*a,501); 
phi = linspace(0,2*pi,501);
[R,Phi] = meshgrid(r,phi);
X = R.*cos(Phi);
Y = R.*sin(Phi);

And I plot all my figures by using the code segment:

figure()
h = pcolor(X,Y,abs(u_sum).^2); % u_sum is an electric field distribution
set(h,'EdgeColor','none');
box on
grid on
axis equal
xlim([-1,1]*r(end)/sqrt(2));
ylim([-1,1]*r(end)/sqrt(2));
colormap(hot);
colorbar;
xlabel('x');
ylabel('y');
title(['Title'])
hold on
rectangle('Position',[-1,-1,2,2]*a,'Curvature',1,...
    'LineWidth',1,'EdgeColor','w','FaceColor','None',...
    'LineStyle','--')
hold off
set(gca,'Layer','top')

The output of this code is:

Now, I want to draw a circle full of ones with radius "a" and place it on the same grid. Thus, I want the circle at the center of the above picture to be filled with ones, and zeros at rest. How can I do that using pcolor and the same grid?

Alternatively, how can I implement a Gaussian shape for the same grid using pcolor?