* ext/bigdecimal/lib/bigdecimal/math.rb (atan): atan(Infinity) is
PI/2. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@25063 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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@ -1,4 +1,7 @@
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Thu Sep 24 02:08:35 2009 Nobuyoshi Nakada <nobu@ruby-lang.org>
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Thu Sep 24 02:21:23 2009 Nobuyoshi Nakada <nobu@ruby-lang.org>
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* ext/bigdecimal/lib/bigdecimal/math.rb (atan): atan(Infinity) is
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PI/2.
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* ext/bigdecimal/lib/bigdecimal/math.rb (atan): reduce loop with
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the formula of the double corner. based on a patch from
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@ -117,22 +117,16 @@ module BigMath
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# Computes the arctangent of x to the specified number of digits of precision.
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#
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# If x is infinite or NaN, returns NaN.
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# If x is NaN, returns NaN.
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def atan(x, prec)
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raise ArgumentError, "Zero or negative precision for atan" if prec <= 0
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return BigDecimal("NaN") if x.infinite? || x.nan?
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return BigDecimal("NaN") if x.nan?
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pi = PI(prec)
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if neg = x < 0
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x = -x
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end
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if x.round(prec) == 1
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return pi / (neg ? -4 : 4)
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elsif inv = x > 1
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x = 1 / x
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end
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if dbl = x > 0.5
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x = (-1 + sqrt(1 + x**2, prec))/x
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end
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x = -x if neg = x < 0
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return pi.div(neg ? -2 : 2, prec) if x.infinite?
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return pi / (neg ? -4 : 4) if x.round(prec) == 1
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x = 1 / x if inv = x > 1
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x = (-1 + sqrt(1 + x**2, prec))/x if dbl = x > 0.5
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n = prec + BigDecimal.double_fig
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y = x
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d = y
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@ -21,7 +21,7 @@ class TestBigMath < Test::Unit::TestCase
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assert_equal(0.0, sqrt(BigDecimal("-0"), N))
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assert_raise(FloatDomainError) {sqrt(BigDecimal("-1.0"), N)}
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assert_raise(FloatDomainError) {sqrt(NAN, N)}
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assert_equal(PINF, sqrt(PINF, N))
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assert_raise(FloatDomainError) {sqrt(PINF, N)}
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end
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def test_sin
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@ -56,6 +56,7 @@ class TestBigMath < Test::Unit::TestCase
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assert_equal(0.0, atan(BigDecimal("0.0"), N))
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assert_in_delta(Math::PI/4, atan(BigDecimal("1.0"), N))
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assert_in_delta(Math::PI/6, atan(sqrt(BigDecimal("3.0"), N) / 3, N))
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assert_in_delta(Math::PI/2, atan(PINF, N))
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end
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def test_exp
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