Hello world,
I'm new at julia, and trying it out as a replacement for matlab and other
computer algebra systems. I'm a bit stuck with sparse matrices: I have
largeish matrices (10^6 x 10^6) that are very sparse, and
want to know their rank and nullspace. (the matrices decompose by blocks,
so the nullspace should be expressible as a sparse matrix).
I tried with the latest (github) julia 0.5:
julia> nullspace(sparse([1],[1],[1]))
ERROR: MethodError: `nullspace` has no method matching
nullspace(::SparseMatrixCSC{Int64,Int64})
julia> nullspace(full(sparse([1],[1],[1])))
1x0 Array{Float64,2} # I'm a bit unhappy here, I was hoping to get a
rational answer.
julia> nullspace([1//1])
1x0 Array{Float32,2} # yikes! I'm down to 32 bits floats now.
julia> rank(sparse([1],[1],[1.0]))
ERROR: MethodError: `svdvals!` has no method matching
svdvals!(::SparseMatrixCSC{Float64,Int64})
julia> rank([1.0])
ERROR: MethodError: `rank` has no method matching rank(::Array{Float64,1})
julia> rank([1 0;0 1])
2 # finally something that works...
Many thanks in advance! Laurent
