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Brian Kessler authored
Branch cuts for the elementary complex functions along real or imaginary axes should be resolved in floating point calculations by one-sided continuity with signed zero as described in: "Branch Cuts for Complex Elementary Functions or Much Ado About Nothing's Sign Bit" W. Kahan Available at: https://people.freebsd.org/~das/kahan86branch.pdf And as described in the C99 standard which is claimed as the original cephes source. Sqrt did not return the correct branch when imag(x) == 0. The branch is now determined by sign(imag(x)). This incorrect branch choice was affecting the behavior of the Trigonometric/Hyperbolic functions that use Sqrt in intermediate calculations. Asin, Asinh and Atan had spurious domain checks, whereas the functions should be valid over the whole complex plane with appropriate branch cuts. Fixes #6888 Change-Id: I9b1278af54f54bfb4208276ae345bbd3ddf3ec83 Reviewed-on: https://go-review.googlesource.com/46492 Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by:
Russ Cox <rsc@golang.org>
802a8f88