Getting indices of all unique rows

I have a matrix "M" with 1,000 rows and 5 columns. The first column is the row number and columns 2:5 are ordinal numbers (-1, 0, 1). To get the number of unique rows with respect to columns 2:5 I've used the following:

   uM = unique(M(:, 2:5));

But what I really want is the row indices for each unique row.

Let's say that M is really:

[1 0 1 1 -1; 2 1 0 -1 -1; 3 0 1 1 -1; 4 -1 0 -1 1 ]

I'd like to obtain a cell array vector that has:

{ (1, 3), 2, 4 }

Any ideas?

Thanks!

Answer 1

[per isakson]

Read the documentation on unique and note that there is a second and third output argument. Doc says:

    [C,ia,ic] = unique(A,'rows')