Matrix Multiplication in Power Query M. Test example = MatrixMultiplication(#table({"A","B"},{{1,2},{3,4}}), #table({"A","B"},{{1,2},{3,4}}))

MatrixMultiplication.m

(A,B) =>
let
    //vector multiplication
    dotProduct = (v1,v2) =>
            List.Accumulate(
                List.Zip({v1,v2}),
                         0,
                         (agg,_)=>
                                agg+(_{1}*_{0}))

in 
    Table.FromRows(
        List.Accumulate(Table.ToRows(A),
                        {},
                        (_,ai)=>
                               _& { List.Accumulate(Table.ToColumns(B),
                                                    {},
                                                    (_,bj)=>
                                                           _&{ dotProduct(ai,bj) })
                                    })
    )