On Tue, 29 Apr 2008, "Travis E. Oliphant" apparently wrote: > x[i,:] * A * x[:,i] This need is also fully met by Proposal 5. It is just a matter of syntax and sticking with matrices. <URL:http://www.scipy.org/MatrixIndexing#proposal-5> E.g., x.rows(i) * A * x.cols(i) Cheers, Alan Isaac