Use equation in for loop

I have a 2d array that I'm reading in that is 100x2. I have the following equation that needs to loop through and calculate starting at the next row

 total=total+(y1+y2)*(x1-x2)

Here's what I've started with, I'm just not sure how to set it up

 [nrows,ncols] = size(data);

 for m=1:1:nrows
    for n=1:1:ncols
        total = total+

[Walter Roberson]

What are x1, x2, y1, y2? How do they relate to the content of the image? How do they relate to the row or column numbers?

[triztyme]

Here is a sample of the data

(x) (y)

0.000 /0.000

0.023 /64.792

0.072 /178.808

0.122 /213.286

0.172 /225.909

0.222 /224.443

.......

so it should go

 total=toal+(0.000+64.792)*(.023-0.000)

then to the next row

 total=total+(64.792+178.808)*(0.072-0.023)

and keep looping through all data

Answer 1

[MHN]

   data = rand(100,2); % just for an example
   [nrows,ncols] = size(data);
   total = 0;
   for m=1:nrows-1
          total = total+ (data(m,2)+data(m+1,2))*(data(m,1)+data(m+1,1));
    end

[triztyme]

thank you! I am required to use a for loop, if it were up to me I would use your other example

Answer 2

[Walter Roberson]

hint: x(m), x(m+1)

[triztyme]

thank you for your input

Answer 3

[CS Researcher]

You can avoid the for loop by:

data = rand(100,2); % just for an example
N = size(data,1);
total = sum((data(1:N-1,2) + data(2:N,2)) .* (data(1:N-1,1) + data(2:N,1)));