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* ext/bigdecimal/lib/bigdecimal/math.rb (atan): refined.

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git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@25057 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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nobu 2009-09-23 12:25:20 +00:00
parent 98b0d9f922
commit 8c3926aea0
2 changed files with 15 additions and 0 deletions
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4
ChangeLog
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@ -1,3 +1,7 @@
Wed Sep 23 21:25:20 2009 Nobuyoshi Nakada <nobu@ruby-lang.org>
* ext/bigdecimal/lib/bigdecimal/math.rb (atan): refined.
Wed Sep 23 17:08:30 2009 Nobuyoshi Nakada <nobu@ruby-lang.org> Wed Sep 23 17:08:30 2009 Nobuyoshi Nakada <nobu@ruby-lang.org>
* parse.y (assign_in_cond): also should warn assignment to dvar in * parse.y (assign_in_cond): also should warn assignment to dvar in

11
ext/bigdecimal/lib/bigdecimal/math.rb
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@ -121,6 +121,15 @@ module BigMath
def atan(x, prec) def atan(x, prec)
raise ArgumentError, "Zero or negative precision for atan" if prec <= 0 raise ArgumentError, "Zero or negative precision for atan" if prec <= 0
return BigDecimal("NaN") if x.infinite? || x.nan? return BigDecimal("NaN") if x.infinite? || x.nan?
pi = PI(prec)
if neg = x < 0
x = -x
end
if x == 1
return pi / (neg ? -4 : 4)
elsif inv = x > 1
x = 1 / x
end
n = prec + BigDecimal.double_fig n = prec + BigDecimal.double_fig
y = x y = x
d = y d = y
@ -134,6 +143,8 @@ module BigMath
y += d y += d
r += 2 r += 2
end end
y = pi / 2 - y if inv
y = -y if neg
y y
end end