https://faculty.cst.temple.edu/~szyld/reports/randCholQR_rev2_report.pdf
Only the trian-gular factor ˆR is needed, so some (exactly) orthogonal Qtmp exists such that Qtmp ˆR = ˆW + E2 = S2S1V + E1 + E2. (17) Analysis of E2 is provided in Section 5.2.4. In step 3, solving the triangular system Q ˆR = V also creates errors. These are analyzed in a row-wise fashion in Section 5.2.5, taking the form