diff options
| author | nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2010-05-12 06:04:59 +0000 |
|---|---|---|
| committer | nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2010-05-12 06:04:59 +0000 |
| commit | 5b20a1398befac93116d69112e12c21533667927 (patch) | |
| tree | 119b93b0b26ff51b4758589ce711616ce7ca4e46 /ext | |
| parent | 851a023843ac4db27c3fb4dc2c4e1a523e0d3831 (diff) | |
* ext/bigdecimal/lib/bigdecimal/math.rb (BigMath#log): improved
precision and performance. [ruby-dev:41295]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@27747 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'ext')
| -rw-r--r-- | ext/bigdecimal/lib/bigdecimal/math.rb | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/ext/bigdecimal/lib/bigdecimal/math.rb b/ext/bigdecimal/lib/bigdecimal/math.rb index 07efcbe099..41fc69f66c 100644 --- a/ext/bigdecimal/lib/bigdecimal/math.rb +++ b/ext/bigdecimal/lib/bigdecimal/math.rb @@ -190,8 +190,10 @@ module BigMath one = BigDecimal("1") two = BigDecimal("2") n = prec + BigDecimal.double_fig - if (expo = x.exponent) < 0 + if (expo = x.exponent) < 0 || expo >= 3 x = x.mult(BigDecimal("1E#{-expo}"), n) + else + expo = nil end x = (x - one).div(x + one,n) x2 = x.mult(x,n) @@ -206,7 +208,7 @@ module BigMath y += d end y *= two - if expo < 0 + if expo y += log(BigDecimal("10"),prec) * BigDecimal(expo.to_s) end y |