#8539: Data.Complex shouldn't use default implementation of (**) -------------------------------------+------------------------------------- Reporter: jjaredsimpson | Owner: Type: bug | Status: patch Priority: low | Milestone: Component: Prelude | Version: 7.6.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Unknown/Multiple Type of failure: Incorrect result | Difficulty: Easy (less than 1 at runtime | hour) Test Case: | Blocked By: Blocking: | Related Tickets: -------------------------------------+------------------------------------- Comment (by yalas): Testing [https://ghc.haskell.org/trac/ghc/attachment/ticket/8539/complex_functions.pa... complex_functions.patch]: ||= =||= Double =||= Complex Double (patched) =||= Complex Double (current) =|| || 1/0 || Infinity || Infinity :+ 0.0 || Infinity || || 1/0*0 || Nan || NaN :+ 0.0 || NaN :+ NaN || || 1/0/0 || Infinity || Infinity :+ 0.0 || NaN :+ NaN || || 1/0/2 || Infinity || Infinity :+ 0.0 || NaN :+ NaN || || (1/0)*(1/0) || Infinity || Infinity :+ 0.0 || NaN :+ NaN || || sqrt (1/0) || Infinity || Infinity :+ 0.0 || NaN :+ NaN || || exp (1/0) || Infinity || Infinity :+ 0.0 || NaN :+ NaN || || exp (-1/0) || 0.0 || 0.0 :+ 0.0 || NaN :+ NaN || || log (1/0) || Infinity || Infinity :+ 0.0 || NaN :+ NaN || || log (-1/0) || NaN || Infinity :+ 3.141592653589793 || NaN :+ NaN || || 0!**0 || 1.0 || 1.0 :+ 0.0 || NaN :+ NaN || || 0!**2 || 0.0 || 0.0 :+ 0.0 || NaN :+ NaN || || 0!**(-2) || Infinity || Infinity :+ 0.0 || NaN :+ NaN || || 2!**4 || 16.0 || 16.0 :+ 0.0 || 15.999999999999998 :+ 0.0 || || 3!**1 || 3.0 || 3.0 :+ 0 || 3.0000000000000004 :+ 0.0 || || sqrt (-4) || NaN || 0.0 :+ 2.0 || (-0.0) :+ 2.0 || This even partially fixes old raise to power implementation: ||= =||= Double =||= Complex Double (patched) =||= Complex Double (current) =|| || exp (log 0 * 2) || 0.0 || 0.0 :+ 0.0 || NaN :+ NaN || || exp (log 0 * 0) || 1.0 || NaN :+ 0.0 || NaN :+ NaN || || exp (log 0 * (-2)) || Infinity || Infinity :+ 0.0 || NaN :+ NaN || What do you think? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8539#comment:12 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler