[GHC] #14927: Hyperbolic area sine is unstable for (even moderately) big negative arguments.

[GHC]

#14927: Hyperbolic area sine is unstable for (even moderately) big negative
arguments.
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        Reporter:  leftaroundabout   |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  libraries/base    |              Version:  8.2.1
      Resolution:                    |             Keywords:  Floating
                                     |  IEEE754 trigonometric
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  Incorrect result  |  Unknown/Multiple
  at runtime                         |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by leftaroundabout):

 Yes, the cut-offs come out different, but it doesn't really matter: `sqrt
 (1 + x*x)` is still stable and accurate for a long way even when `x` is so
 big that `1 + x*x == x*x`. So, whereas it's important that `huge` should
 not be ''smaller'' than `1/sqrt epsilon ≈ 6.7e7`, it ''can'' actually be
 much bigger: `1e100` would also work in case of `Double`. Therefore,
 `1/epsilon ≈ 4.5e15` is a safe compromise that's presumably less likely to
 give new surprising corner-cases.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14927#comment:6>
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