Circle looks like ellipse

[Aziz YÜCELEN]

Hi 

I want to plot a simple tear drop-like a function.  I have a problem while plot screen. Circle looks like ellipse so that  X and Y axis scale not equal. Full code is below. Please can you help me ? 

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%circle center: (center_x,center_y)

%circle radius:radius

% y axis component of any top point

% (x1,y1)->(x2,y2)<-(x3,y3)

%

function tear_drop(center_x,center_y,radius,top_y_point)

th = linspace( pi, (2*pi), 100);

R = radius/2;  %or whatever radius you want

x = R*cos(th)+center_x;

y = R*sin(th)+center_y;

x1=center_x-(R);

x2=center_x;

x3=center_x+(R);

y1=y3=0;

y2=top_y_point;

plot([x1 x2], [y1 y2],'r')

hold on

plot([x2 x3], [y2 y3],'r')

hold on

plot(x,y,'k');

hold on

endfunction

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