# Can I draw the figure with the help of MATLAB code ?

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Mabud Sarkar on 28 Aug 2019
Commented: Star Strider on 20 Aug 2020
I want to figure out the following graph to show map between two annular region as follows:
Here B is subset of A and we want to show the map from (A - B) to B.
How do I plot this graph?
Can I draw the figure with the help of MATLAB code or Mathematica ?
In that case what would be the Matlab Code ?
Help me

Star Strider on 28 Aug 2019
Try this:
circx = @(r,a) r.*cos(a);
circy = @(r,a) r.*sin(a);
a = linspace(0, 2*pi);
figure
fill(0.2*circx(1,a)-0.5, 0.2*circy(1,a), 'g')
hold on
fill(0.1*circx(1,a)-0.5, 0.1*circy(1,a), 'w')
fill(0.2*circx(1,a)+0.5, 0.2*circy(1,a), 'g')
fill(0.1*circx(1,a)+0.5, 0.1*circy(1,a), 'w')
hold off
axis equal
xlim([-1 1])
annotation('textarrow',[0.35, 0.7], [0.58, 0.58])
text(-0.6, 0.15, 'A-B')
text([-0.5 0.5], [0 0], 'B', 'HorizontalAlignment','center')
text(0, 0.2, '\itf\rm', 'FontSize',15)
Experiment to get the result you want.
Mabud Sarkar on 20 Aug 2020
Edited: Mabud Sarkar on 20 Aug 2020
text([-0.5 0.5], [0 0], 'B', 'HorizontalAlignment','center')
Why did you use both [-0.5 0.5] and [0 0] ?
But in the previous line you used only
text(-0.6, 0.15, 'A-B')
Can you please explain the above ?
Second question,
why in case of annotation textarrow, we are allowed only points between 0 and 1 ?
Why not negative points ?
Star Strider on 20 Aug 2020
They are two separate text calls displaying two different strings.
The ‘B’ is displayed twice, once in each circle, so two positions, one for each. (I could have used two different text calls. Using one text call with two coordinates is more efficient.)
The ‘A-B’ is displayed once, so it only needs one set of coordinates.

KALYAN ACHARJYA on 28 Aug 2019
Edited: KALYAN ACHARJYA on 28 Aug 2019
Please note: I have done the Jugaad here. I have no idea what the plot represents?
I tried it for 10 minutes, hence I posted it as 2nd answer.
x=[5,5,15,15];
y=[5,5,5,5];
r=[2,1,2,1];
theta=0:pi/50:2*pi;
for i=1:4
x_circle=r(i)*cos(theta)+x(i);
y_circle = r(i)*sin(theta)+y(i);
plot(x_circle,y_circle);
if r(i)==max(r)
h=fill(x_circle,y_circle,'g');
else
h=fill(x_circle,y_circle,'w');
end
hold on;
end
text(x(1),y(1)+3,'A');
text(x(1),y(1)+1.5,'A-B');
text(x(3),y(3)+3,'A');
text(x(1),y(1),'B');
text(x(3),y(3),'B');
quiver(x(1)+1.3,y(1),10,0);
text(10,5.3,'f');
Mabud Sarkar on 28 Aug 2019
Edited: Mabud Sarkar on 28 Aug 2019
Thank you for your answer. But how the arrow will touch the circle B ?
Actually this figures represnts mapping between two annular region in Complex analysis of M.Sc. mathematics ?

Steven Lord on 28 Aug 2019
A regular N-sided polygon (for large N) is visually indistinguishable from a circle. Try:
>> A = nsidedpoly(1000, 'Center', [0 0], 'Radius', 2);
>> B = nsidedpoly(1000, 'Center', [0 0], 'Radius', 1);
>> C = subtract(A, B);
>> plot(C, 'FaceColor', 'g')
>> axis equal
To make copies of the polyshape objects A and B at a different location, call translate on them (specifying a different variable name as output.) See this documentation page for more functions that you can use to operate on polyshape objects.
For the arrow, call annotation. For the letters, call text.
Mabud Sarkar on 28 Aug 2019
Please add the rest code because I can not get it at the beginning. However I will grasp the code for future. So please add the complete code with the figure.