Before revision:  In some parameter regimes, our algorithm is best known, and essentially confirms a conjecture of Ailon and Chazelle}  ] ] .
After revision:  In some parameter regimes, our algorithm is best known, and essentially confirms a conjecture of Ailon and Chazelle} ) for essentially the same range of sparsity as in the best-known such transform due to Ailon and Rauhut ] ] .