“…Examples of such methods, in which C(x)=-O, Yk --F(Xk/)--F(Xk) and Wk Sk, are a single-rank update method due to G. McCormick (see Pearson [23]), obtained by taking 4 -"", and the Broyden-Fletcher-Goldfarb-Shanno (BFGS) method [4], [5], [16], [18], [28], [12], [26], which results when 4 is the subspace of symmetric matrices in "". In both of these methods, the norm on R"" after k iterations is taken to be weighted Frobenius norm I1' []w, where W is a positive-definite, symmetric matrix satisfying Wyk Sk (SO again, g ).…”