(with *1* replacing if *q**i**=0*) where a scalar
function is chosen so that

where *e* is a small positive number and *c* is chosen so that has unit 2-norm, i.e., This in turn implies that *f* has unit 2-norm.

Similarly,
if *w**0**=* ¥, the conclusion follows by letting *w**0**®** * ¥ in the above.