How to operate on One Column of A matrix while the other Columns stay connected row-wise to the column we are operating on

Hi, sorry for bad wording but suppose i have this matrix

A =

1 2

1 3

2 5

2 4

4 2

6 1

8 1

I want to find the maximum of the first column while still connect the second value to the output for example if i ask the output of max 1st column of A itu will return the value of :

8   1

moreover, I want to rank the matrix from the largest value, based on column 1 while still connect the first column to the second, the desired output is this:

8   1
6   1
4   2
2   5
2   4
1   3
1   2

how can i do that?

lastly i want to find the average of the third largest value of the above matrix, based on the value of the first column, column wise. The desired output is this:

6   1.333

again, I'm sorry for bad wording, Any help will be greatly appreciated.

Answer 1

[Maxi]

first problem could be solved with

index_max=find(max(A(:,1))==A(:,1)) %find the index of the largest value in the first column
A(index_max,:)
>>ans =

     8     1

[Arief Yoga Randytama]

thanks a lot !