but non-identity matrix
l1 0 0 0 ....
0 l2 0 0 ....
0 0 l3 0 ...
. . .
. . .
. . .
And apply the multishift CG to it. Sum the poles and residues.
Insist that this be the same as the exactly taken square root
where l1,l2,l3 >= 0.
cut at Conjugate gradient. Also copied in Remez, Zolotarev, Chebyshev from
Mike Clark, Tony Kennedy and my BFM package respectively since we know we will
need these. I wanted the structure of
algorithms/approx
algorithms/iterative
etc.. to start taking shape.
