[GHC] #9564: Floating point subnormals overrounded on output

[GHC]

#9564: Floating point subnormals overrounded on output
-------------------------------------+-------------------------------------
              Reporter:  jrp         |            Owner:  simonmar
                  Type:  bug         |           Status:  new
              Priority:  normal      |        Milestone:
             Component:  Runtime     |          Version:  7.8.3
  System                             |         Keywords:
            Resolution:              |     Architecture:  x86_64 (amd64)
      Operating System:  MacOS X     |       Difficulty:  Unknown
       Type of failure:  Incorrect   |       Blocked By:
  result at runtime                  |  Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------

Comment (by rwbarton):

 Overrounding in what sense? Do we have a spec for the Show Float, Show
 Double instances? (Honest question.)

 I thought that we tried to show the fewest number of significant figures
 that would round unambiguously to the true value of the floating-point
 number (which is
 `1.40129846432481707092372958328991613128026194187651577175706828388979108268586060148663818836212158203125e-45`
 in this case). In that case `1.0e-45` would be correct since
 `1.401...e-45` is the smallest positive Float and `1.0e-45` is more than
 half of it. However, I don't recall where I got that impression.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9564#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler