Does anyone know if it is possible to not include the diagonal when using the LowerTriangular() function or if there is a function that can exclude the diagonal from the output? LowerTriangular() would work perfectly for what I am doing if the diagonal was not included.
No, but there is LinAlg.UnitLowerTriangular which masks the diagonal with 1.
Or you can define your own type?
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You could use a view of a triangular matrix
view(L,:,2:end)
No, unfortunately @view L[:, 2:end] will just drop the first column. The closest thing here is probably the tril and tril! functions, which allow a second argument to specify the diagonal from which the given matrix should be masked.
Also, is this related? Perhaps the same question?
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Just a concrete example to emphasize @mbauman’s idea:
julia> using LinearAlgebra
julia> a = rand(1:5,5,5)
5×5 Array{Int64,2}:
2 5 2 4 1
2 1 3 2 3
1 4 4 3 1
3 3 1 2 2
3 2 3 5 3
julia> b = tril(a,-1)
5×5 Array{Int64,2}:
0 0 0 0 0
2 0 0 0 0
1 4 0 0 0
3 3 1 0 0
3 2 3 5 0
So, as you see, you just need to feed that optional -1 to the tril function to express your desire for dropping the main diagonal.
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Thank you for the example!