Fix mul! for uninitialized matrices and add interface tests#17

ChrisRackauckas merged 2 commits into

SciML:mainSciML/SparseBandedMatrices.jl:mainfrom

ChrisRackauckas-Claude:interface-check-20260107-133126ChrisRackauckas-Claude/SparseBandedMatrices:interface-check-20260107-133126Copy head branch name to clipboard