I'm wondering if there's a natural data structure for a matrix whose rows
are of different length, in my case strictly growing. The usage is e.g.
representing coefficients in a 2D monomial expansion:
f_00 + f_10 x + f_01 y + f_20 x^2 + f_11 xy + f_02 y^2 + …
So I want to do the following:
F=TreeMatrix(Float64,1:n,n)
F[1,1] # return f_00
F[1,2] # out of bounds error
F[1,1] # returns f_10
F[1,2] # returns f_01
F[1,3] # out of bounds error
It's easy to implement myself I suppose (probably more efficient to wrap a
Vector{Float64} than a Vector{Vector{Float64}}), but I was just curious if
such a thing exists.
The next step on top of this is a data structure for banded linear
operators on trees.
