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    %% Sort Rows of Tall Matrix
% Sort the rows of a tall matrix using different sorting orders, return the
% top rows, and view the results.
%
% Create a 100-by-5 matrix of random integers. Convert the in-memory array
% into a tall array.
X = randi(20,100,5);
TX = tall(X)

%%
% Sort the rows of |TX| in descending order and return the top 15 rows. By
% default, |topkrows| sorts using the first column of the matrix. For any
% rows that have equal elements in a particular column, the sorting is
% based on the column immediately to the right. Collect the values into
% memory to view the complete results.
TA = topkrows(TX,15)

%%
T1 = gather(TA)

%%
% When called with three input arguments, |topkrows| bases the sort
% entirely on the column specified in the third argument.
%
% Sort |TX| in descending order using the values in the third column, and
% return the top 20 rows. Collect the values into memory to view the
% complete results.
TB = topkrows(TX,20,3)

%%
T2 = gather(TB)

%%
% If you sort using only one column, then rows that have equal values in
% the specified column remain in their original order.

%%
% Specify two columns to sort by; for example, columns 3 and 4. Collect the
% values into memory to view the complete results.
TC = topkrows(TX,20,[3 4])

%%
T3 = gather(TC)

%%
% |topkrows| sorts by column 3, and then for any rows with equal
% values in column 3, sorts by column 4.