How can I use accumarray in order to evaluate the place where users spend most of their time?

Hello everybody, I would like to make a question. I have the array Z with

Z(:,1)=USER_ID
Z(:,2)=PLACE
Z(:,3)=DATE
Z(:,4)=TIME

For each user I compute the most visited location as

% L =  accumarray(Z(:,1),Z(:,2),[max(Z(:,1)) 1],@mode);

How can I evaluate the location in which users spend most of their time? For each location visited by each user I should evaluate the timespan in days and then choose the location where this timespan is maximum.

Thanks for your support.

[Andrei Bobrov]

Z(:,4) - interval of time (in hours or minutes)?

[Emanuele Massaro]

Z(:,4) is in form of "hhmmss". But for now I just care about the timespan in days Z(:,3). I am doing

L1 =  accumarray(Z(:,1:2),Z(:,4),[max(Z(:,1)) max(Z(:,2))],@sum);

What do you think?