Last night I was helping an HPGCC user build GSL (GNU Scientific Library) for the 50g. After I got it compiled I needed to create a simple test case and opted for a complex square root. When I read the documentation (http://www.gnu.org/software/gsl/manual/html_node/Complex-Numbers.html) this gem was present:

Quote:The 28/48 was not the only source of validation, but interesting that it is mentioned and possibly implied as a trusted source.

For multiple-valued functions the branch cuts have been chosen to follow the conventions of Abramowitz and Stegun in theHandbook of Mathematical Functions. The functions return principal values which are the same as those in GNU Calc, which in turn are the same as those inCommon Lisp, The Language (Second Edition)and theHP-28/48 series of calculators.