complex multiplication

[David Hough]

The definitive tome on the signs of zeros and infinities in complex
multiplication is Kahan's "Branch Cuts for Complex Elementary
Functions, or Much Ado About Nothing's Sign Bit" of which the
version dated 7 September 1987 was distributed with the floating-point
indoctrination lecture notes as part of set 14.  If you didn't register
for those lectures, you won't have those notes (and can't get them)
but a version was "prepared for the joint IMA/SIAM conference on
'the state of the art in numerical analysis' held at the 
University of Birmingham, England, April 14-18, 1986, for which
the proceedings have been published in 1987 by the Oxford University
Press, edited by M.J.D. Powell and A. Iserles."

But the 1987 version is labeled "work in progress" although I don't know
how much work has progressed.