Excel – find smallest difference between value and list, and associated index

I have 2 lists of values in Excel (B2:B5002 and K2:26). For each of the values in column K, I need to find the closest value in column B, and then return the corresponding number in column A.

I have worked out how to find the smallest difference between the values in columns B and K, but I can’t work out how to now get the corresponding value from column A.

Here is an example of what I have already:

    A   B      K   
    1   7.55   9
    2   9.33   3
    3   1.05   7
    4   2.38
    5   6.22

What I would like is for column L to return 2, 4, 1 (the values in A that correspond to the closest values in B). So far, I have used this code in column L to find the smallest difference:

    =MIN(ABS($B$1:$B$5-$L1))

and then I press CTRL+SHFT+ENTER to get it to be an array formula and then drag it into the other rows of column L. I don’t know what to do to get the numbers from A that correspond to these differences! Can anyone help out?

I just thought I would mention that I have done this fine in Matlab, but I am trying to do the same thing in Excel for a student who can’t use Matlab. They could do it manually, but I am trying to save them some time.

=INDEX(A$2:A$5002,MATCH(MIN(ABS(B$2:B$5002-K2)),ABS(B$2:B$5002-K2),0))

Tags: excelexcel, list