Looping matrice column by subtraction

I have a 84x7 matrices. On the entire column 2 and 4, they need to be subtracted from higher number - lower and loop through the whole 84 rows and put them into a new 84x1 vector. How can this be done? let 4x4 matrix a = [x 3 2 y; x 4 1 y; x 1 6 y; x 2 7 y; x 5 1 y;

             b=          [3-2   4-1   6-1   7-2  5-1]

             b=          [1      3     5      5   4 ]

[madhan ravi]

A small example? And your desired output?

Answer 1

[madhan ravi]

EDIT 2

a = randi([0 9],84,7) %fake data to test
a1=a(:,2) %column you want to extract
a2=a(:,5) %column you want to extract
a=[a1 a2] %two columns stored in a matrix  , sorry I missed this line which caused the error
idx = find(a1<a2)
a(idx,:)=fliplr(a(idx,:))
b = a(:,1) - a(:,2) % as column vector
b1 = b'  %row vector

[madhan ravi]

if it doesn't meet your requirement let know

[Young Lee]

Sorry It doesnt work,

[madhan ravi]

See edited answer now , no need loop to attain the desired result

[Young Lee]

nope ,

[madhan ravi]

It’s like you gave in the example right? Am I missing something?

[Young Lee]

here's code I have used , I figured out all the odd rows were wrong in value as well

x = myreesult2 %EDITED a1= x(:,2); a2= x(:,5); idx = find(a1<a2); %its column 2 & 5 out of 84x7 matrice x(idx,:)=fliplr(x(idx,:)); b = x(:,2) - x(:,5) % as column vector

[madhan ravi]

use abs(the_value) to get positive result, if you don’t want to use abs() upload the matrix which you are testing because as you can see it works very well for the example you gave here

[madhan ravi]

Can you upload x(:,2) & x(:,5) datas here so that it can be tested

[Young Lee]

sure, have look on a1 & a2

[madhan ravi]

check the edited code now

[Young Lee]

thanks for your patience and help :)

[madhan ravi]

Anytime:)