MATLAB Answers

how can i calculate a complex polygon with coordinates in matlab ?

4 views (last 30 days)
ADNAN KIRAL on 19 Oct 2020
Commented: ADNAN KIRAL on 19 Oct 2020
how can I calculate A complex polygon in Matlab?
image shows what I need to calculate in Matlab. do you guys have any code for that ? or are there any Matlab command which can calculate it by coordinates?
thanks in advance


Show 1 older comment
ADNAN KIRAL on 19 Oct 2020
thanks for your reply.
calculation of the area !.
I have a large number of coordinates. If I can code it in Matlab. I will replace with my coordinates. So that I need to know how to calculate the area of such shape.

Sign in to comment.

Accepted Answer

Ameer Hamza
Ameer Hamza on 19 Oct 2020
The equation in your comment can be written in MATLAB like this
A = 1/2*sum(x(1:end-1).*y(2:end)-y(1:end-1).*x(2:end));


Show 4 older comments
ADNAN KIRAL on 19 Oct 2020
well, suppose, you have a number of coordinates.
this is total area A = 1/2*sum(x(1:end-1).*y(2:end)-y(1:end-1).*x(2:end));
up to here, it is ok,
assume i have 100 coordinates.
coordinate 1 (first one), total area= 1cm^2
coordinate 2 (second one), total area= 5cm^2
.. so on..
I just want to give a number to each coordinate (like 1,2,3,4,5....). this part will appear in x coordinate, total areas will be in the y-axis. that is all I want.
like this;
Ameer Hamza
Ameer Hamza on 19 Oct 2020
You can try something like this
A = zeros(1, numel(X)-2);
for i = 1:numel(A)
x = X(1:i+2);
y = Y(1:i+2);
A(i) = 1/2*sum(x(1:end-1).*y(2:end)-y(1:end-1).*x(2:end));

Sign in to comment.

More Answers (2)

Deeds on 19 Oct 2020
You can use polyarea for accomplishing your task. The documentation is here:
Hope that helps!

  1 Comment

ADNAN KIRAL on 19 Oct 2020
thanks for reply.
one more question please ? how can I get coordinate vs. area ( at the end, I need to know how the area is increasing with coordinate change)
I have tried "cumsum" Matlab command, but it did not work. it gave the total area. thanks

Sign in to comment.

Steven Lord
Steven Lord on 19 Oct 2020
If you want to do more than just compute its area I would use polyshape for that.
>> x = [7 7 5 3 -5 0 -8 2 -4];
>> y = [-7 3 -6 3 3 8 3 -3 -8];
>> P = polyshape(x, y);
>> plot(P)
There are a number of questions you can ask about a polyshape and a number of operations you can perform on one.


Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by