diff options
| author | nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2016-07-07 07:37:55 +0000 |
|---|---|---|
| committer | nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2016-07-07 07:37:55 +0000 |
| commit | 9bb27fa318928464f5ab66649a75bbd034307baa (patch) | |
| tree | 0ab24af61bc3fe18bd6fccc658fd2350a03c5984 | |
| parent | 415059abf14c63979621be79512713772f9e9970 (diff) | |
numeric.c: round nearly middle value
* numeric.c (flo_round): [EXPERIMENTAL] adjust the case that the
receiver is close to the exact but unrepresentable middle value
of two values in the given precision.
http://d.hatena.ne.jp/hnw/20160702
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@55604 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
| -rw-r--r-- | ChangeLog | 7 | ||||
| -rw-r--r-- | numeric.c | 11 | ||||
| -rw-r--r-- | test/ruby/test_float.rb | 5 |
3 files changed, 21 insertions, 2 deletions
@@ -1,3 +1,10 @@ +Thu Jul 7 16:37:53 2016 Nobuyoshi Nakada <nobu@ruby-lang.org> + + * numeric.c (flo_round): [EXPERIMENTAL] adjust the case that the + receiver is close to the exact but unrepresentable middle value + of two values in the given precision. + http://d.hatena.ne.jp/hnw/20160702 + Thu Jul 7 16:31:07 2016 Nobuyoshi Nakada <nobu@ruby-lang.org> * io.c (rb_io_s_foreach, rb_io_s_readlines): convert arguments @@ -1990,7 +1990,7 @@ rb_int_truncate(VALUE num, int ndigits) static VALUE flo_round(int argc, VALUE *argv, VALUE num) { - double number, f; + double number, f, x; int ndigits = 0; if (rb_check_arity(argc, 0, 1)) { @@ -2005,7 +2005,14 @@ flo_round(int argc, VALUE *argv, VALUE num) } if (float_invariant_round(number, ndigits, &num)) return num; f = pow(10, ndigits); - return DBL2NUM(round(number * f) / f); + x = round(number * f); + if (x > 0) { + if ((x + 0.5) / f <= number) x += 1; + } + else { + if ((x - 0.5) / f >= number) x -= 1; + } + return DBL2NUM(x / f); } static int diff --git a/test/ruby/test_float.rb b/test/ruby/test_float.rb index 06b1d85242..2684cd8eab 100644 --- a/test/ruby/test_float.rb +++ b/test/ruby/test_float.rb @@ -447,6 +447,11 @@ class TestFloat < Test::Unit::TestCase assert_raise(TypeError) {1.0.round(nil)} def (prec = Object.new).to_int; 2; end assert_equal(1.0, 0.998.round(prec)) + + assert_equal(+5.02, +5.015.round(2)) + assert_equal(-5.02, -5.015.round(2)) + assert_equal(+1.26, +1.255.round(2)) + assert_equal(-1.26, -1.255.round(2)) end def test_floor_with_precision |