Unique Columns Certain Rows

Get the "Unique Columns" of a double matrix, with regard to certain rows and tolerance

Unique Columns Certain Rows is a (very) small function set, which given a double matrix A forms a second matrix B containing the columns of A which have the same value (below a tolerance) in a set of rows specified by a logical vector. Additionally, it outputs a vector which has the "category" to which each column of A belongs.
PS: Current version doesn't guarantee anything about the elements in the "non determinant" rows of A. B will contain those corresponding to the last tested column.

Graphical example:

A= [ 1 1 2 3
2 1 1 1
4 4 4 3
5 6 6 6 ]

whichRows= [ true
false
true
false ]
tol=1

[B,indexVector]=uniqueColumnsCertainRows(A,whichRows,tol) =>

B= [ 1 2 3
1 1 1
4 4 3
6 6 6 ]

indexVector=[1,1,2,3]