references:

	THE STATE OF THE ART IN NUMERICAL ANALYSIS
        edited by ISERLES and POWELL:
		Chapter 7 contains an artical on branch cuts and numerical algorithms for complex multivalued elementary
		functions: sqrt, ln, arcsin, arcos, arctan ,arcsinh, arccosh, arctanh, z exp w
		by W. KAHAN of U.C. Berkeley (415-642-6000)

	HANDBOOK OF MATHEMATICAL FUNCTIONS WITH FORMULAS, GRAPHS, AND MATHEMATICAL TABLES
	edited by ABRAMOWITZ and STEGUN

	APPROXIMATIONS FOR DIGITAL COMPUTERS
	by CECIL HASTINGS:
               contains mostly polynomial aproximations of functions in limited real domains

The speed and accuracy of multivalued complex functions depends on the speed and accuracy of log,
sqrt, and arctan of real numbers.
Arcsin is currently implemented using a polynomial approximation for 0<|x|<1 (found in APPROXIMATIONS FOR DIGITAL COMPUTERS)
and the logarithm definition for the rest of the complex plane. The algorithms in Kahan's article on branch cuts are
different from those implemented in numer.lisp