misc.permute2blockTriangle: new output argument for permutation indices

+misc/permute2blockTriangle.m

-function [triangularMatrix, permutationMatrix] = permute2blockTriangle(A)
+function [triangularMatrix, permutationMatrix, permutationIdx] = permute2blockTriangle(A)
 % MISC.PERMUTE2BLOCKTRIANGLE permutes the matrix A, if possible, to a lower block triangular matrix.
 % The implementation is based on using methods for digraphs, see matlab documentation for digraph.
 %	
@@ -8,6 +8,10 @@ function [triangularMatrix, permutationMatrix] = permute2blockTriangle(A)
 %		permutation matrix such that
 %			triangularMatrix = permutationMatrix * A * permutationMatrix.'
 %
+%	[triangularMatrix, permutationMatrix, permutationIdx] = misc.permute2blockTriangle(A) also 
+%		returns the double array permutationIdx, which contains the indexes for the permutation of
+%		columns of A.
+%
 % Note that inv(permutationMatrix) = permutationMatrix.' (which holds for all so-called
 % permutation matrices).
 
@@ -19,13 +23,13 @@ myDiagraph = digraph(A);
 
 % As agentsBlockNumber defines which agent belongs to which group, the following for loop defines
 % how they will be sorted.
-sortIdx = zeros(size(A, 1), 1);
+permutationIdx = zeros(size(A, 1), 1);
 for blockIdx = numel(blockSize) : -1 : 1
-	sortIdx(sum(blockSize(numel(blockSize):-1:(blockIdx+1))) + (1:blockSize(blockIdx)), 1) ...
+	permutationIdx(sum(blockSize(numel(blockSize):-1:(blockIdx+1))) + (1:blockSize(blockIdx)), 1) ...
 		= find(agentsBlockNumber - blockIdx == 0);
 end
 
-permutationMatrix = full(sparse(1:1:size(A, 1), sortIdx, 1));
+permutationMatrix = full(sparse(1:1:size(A, 1), permutationIdx, 1));
 triangularMatrix = permutationMatrix * A * permutationMatrix.';
 
 end % permute2blockTriangle()
\ No newline at end of file