public CSR GetAdjacencyGraph(CSR P_delta)
        {
            var p = P_delta.CloneMatrix();

            for (var i = 0; i < p.NonZerosCount; i++)
            {
                p.Values[i] = 1;
            }

            var buf = (CSR)p.Multiply(p.Transpose());

            return(buf);
        }