diff options
| author | Alexander Berntsen <alexander@plaimi.net> | 2014-08-18 21:42:12 -0500 |
|---|---|---|
| committer | Austin Seipp <austin@well-typed.com> | 2014-08-18 23:26:19 -0500 |
| commit | 6f6ee6eaa348b1a4815190c4d526d5c81c264fa7 (patch) | |
| tree | 607f3b4db3f206397193fd518f4b889482705d44 | |
| parent | 88b1f99d473e5588378699abeb203c39ea554334 (diff) | |
| download | haskell-6f6ee6eaa348b1a4815190c4d526d5c81c264fa7.tar.gz | |
Make Prelude.abs handle -0.0 correctly (#7858)
Summary:
Make the `Float` and `Double` implementations of `abs` handle -0.0
correctly per IEEE-754.
abs (-0.0::Float) and abs (-0.0::Double) previously returned -0.0, when
they should return 0.0. This patch fixes this.
Signed-off-by: Alexander Berntsen <alexander@plaimi.net>
Test Plan: abs (-0.0::Double) should = 0.0 instead of (-0.0)
Reviewers: ekmett, hvr, austin, rwbarton
Reviewed By: austin, rwbarton
Subscribers: phaskell, trofi, simonmar, relrod, ezyang, carter
Differential Revision: https://phabricator.haskell.org/D145
GHC Trac Issues: #7858
| -rw-r--r-- | libraries/base/GHC/Float.lhs | 10 | ||||
| -rw-r--r-- | libraries/base/changelog.md | 2 |
2 files changed, 8 insertions, 4 deletions
diff --git a/libraries/base/GHC/Float.lhs b/libraries/base/GHC/Float.lhs index e0c4f4ae95..52fc9a99ee 100644 --- a/libraries/base/GHC/Float.lhs +++ b/libraries/base/GHC/Float.lhs @@ -205,8 +205,9 @@ instance Num Float where (-) x y = minusFloat x y negate x = negateFloat x (*) x y = timesFloat x y - abs x | x >= 0.0 = x - | otherwise = negateFloat x + abs x | x == 0 = 0 -- handles (-0.0) + | x > 0 = x + | otherwise = negateFloat x signum x | x == 0.0 = 0 | x > 0.0 = 1 | otherwise = negate 1 @@ -370,8 +371,9 @@ instance Num Double where (-) x y = minusDouble x y negate x = negateDouble x (*) x y = timesDouble x y - abs x | x >= 0.0 = x - | otherwise = negateDouble x + abs x | x == 0 = 0 -- handles (-0.0) + | x > 0 = x + | otherwise = negateDouble x signum x | x == 0.0 = 0 | x > 0.0 = 1 | otherwise = negate 1 diff --git a/libraries/base/changelog.md b/libraries/base/changelog.md index 06c9fa5a97..251ca88cbf 100644 --- a/libraries/base/changelog.md +++ b/libraries/base/changelog.md @@ -18,6 +18,8 @@ enabled, so that the `Monoid` instance for `Proxy` are polykinded like `Proxy` itself is. + * Make `abs` handle (-0.0) correctly per IEEE-754. + ## 4.7.0.1 *Jul 2014* * Bundled with GHC 7.8.3 |