index.md

CurrentModule = CompressedSparseBlocks

CompressedSparseBlocks

Documentation for CompressedSparseBlocks.

Why and when should I use CompressedSparseBlocks?

If you have a computation with an iteration where the time is dominated by a large sparse matrix multiplication,

julia> using LinearAlgebra, SparseArrays, BenchmarkTools

julia> n = 2^22; d = 10; A = sprand(n,n,d/n); x = rand(n);

julia> y = @btime $A*$x;
  909.738 ms (2 allocations: 32.00 MiB)

julia> yt = @btime $(transpose(A))*$x;
  640.637 ms (2 allocations: 32.00 MiB)

you may want to consider the CompressedSparseBlocks.jl package.

julia> using CompressedSparseBlocks

Transforming a SparseMatrixCSC into a SparseMatrixCSB is straightforward, though it might take a few seconds for very large matrices.

julia> Ac = SparseMatrixCSB(A);

but the transformation cost can be eliminated with the speedup from CSB.

julia> yc = @btime $Ac*$x;
  352.766 ms (2 allocations: 32.00 MiB)

julia> yc ≈ y
true

julia> yct = @btime $(transpose(Ac))*$x;
  379.569 ms (3 allocations: 32.00 MiB)

julia> yct ≈ yt
true

API

Modules = [CompressedSparseBlocks]