How to section a matrix?

I am trying to retrieve the latest date entry formation from a table. I have changes the date to a serial number and created a separate matrix with equipment_id and serial number. There are multiple serial numbers for the equipment_id, but just need the highest serial number, since is is the date date entry.

 * euip_id    serial number.
 * -9999866  730537
 * -9999866  733865
 * -9999747  731652
 * -9999747  732028
 * -9999747  729692
 * -9999747  735361

Answer 1

[M]

Maybe using something like this :

M=[-9999866 730537;
-999986 733865;
-9999747 731652;
-9999747 732028;
-9999747 729692;
-9999747 735361];

id=-9999747;   % choose an id

indices where first row of M is equal to the desired id :

index=M(:,1)==id;
index =

6×1 logical array

   0
   0
   1
   1
   1
   1

And take the maximum of the corresponding serial number

max(M(index,2))
ans =

      735361