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* ext/bigdecimal/lib/bigdecimal/math.rb (sin, cos, atan, exp, log):
improved precision and performance. based on a patch from Makoto Yamashita in [ruby-core:25600] and [ruby-core:25602]. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@25013 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
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nobu
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4 changed files with 116 additions and 7 deletions
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@ -1,3 +1,9 @@
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Mon Sep 21 00:07:36 2009 Nobuyoshi Nakada <nobu@ruby-lang.org>
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* ext/bigdecimal/lib/bigdecimal/math.rb (sin, cos, atan, exp, log):
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improved precision and performance. based on a patch from Makoto
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Yamashita in [ruby-core:25600] and [ruby-core:25602].
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Sun Sep 20 11:11:34 2009 Marc-Andre Lafortune <ruby-core@marc-andre.ca>
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* struct.c (rb_struct_equal, rb_struct_eql): Handle comparison of
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@ -49,6 +49,14 @@ module BigMath
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n = prec + BigDecimal.double_fig
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one = BigDecimal("1")
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two = BigDecimal("2")
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x = -x if neg = x < 0
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if x > (twopi = two * BigMath.PI(prec))
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if x > 30
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x %= twopi
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else
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x -= twopi while x > twopi
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end
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end
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x1 = x
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x2 = x.mult(x,n)
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sign = 1
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@ -65,7 +73,7 @@ module BigMath
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d = sign * x1.div(z,m)
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y += d
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end
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y
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neg ? -y : y
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end
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# Computes the cosine of x to the specified number of digits of precision.
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@ -77,6 +85,14 @@ module BigMath
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n = prec + BigDecimal.double_fig
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one = BigDecimal("1")
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two = BigDecimal("2")
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x = -x if x < 0
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if x > (twopi = two * BigMath.PI(prec))
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if x > 30
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x %= twopi
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else
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x -= twopi while x > twopi
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end
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end
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x1 = one
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x2 = x.mult(x,n)
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sign = 1
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@ -99,11 +115,9 @@ 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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# Raises an argument error if x > 1.
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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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raise ArgumentError, "x.abs must be less than 1.0" if x.abs>=1
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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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@ -132,6 +146,7 @@ module BigMath
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return BigDecimal("NaN") if x.infinite? || x.nan?
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n = prec + BigDecimal.double_fig
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one = BigDecimal("1")
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x = -x if neg = x < 0
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x1 = one
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y = one
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d = y
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@ -145,7 +160,11 @@ module BigMath
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d = x1.div(z,m)
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y += d
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end
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y
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if neg
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one.div(y, prec)
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else
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y.round(prec - y.exponent)
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end
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end
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# Computes the natural logarithm of x to the specified number of digits
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@ -159,6 +178,9 @@ module BigMath
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one = BigDecimal("1")
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two = BigDecimal("2")
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n = prec + BigDecimal.double_fig
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if (expo = x.exponent) < 0
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x = x.mult(BigDecimal("1E#{-expo}"), n)
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end
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x = (x - one).div(x + one,n)
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x2 = x.mult(x,n)
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y = x
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@ -171,7 +193,11 @@ module BigMath
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d = x.div(i,m)
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y += d
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end
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y*two
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y *= two
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if expo < 0
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y += log(BigDecimal("10"),prec) * BigDecimal(expo.to_s)
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end
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y
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end
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# Computes the value of pi to the specified number of digits of precision.
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77
test/bigdecimal/test_bigmath.rb
Normal file
77
test/bigdecimal/test_bigmath.rb
Normal file
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@ -0,0 +1,77 @@
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require "test/unit"
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require "bigdecimal"
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require "bigdecimal/math"
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class TestBigMath < Test::Unit::TestCase
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include BigMath
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N = 20
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PINF = BigDecimal("+Infinity")
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MINF = BigDecimal("-Infinity")
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NAN = BigDecimal("NaN")
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def test_const
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assert_in_delta(Math::PI, PI(N))
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assert_in_delta(Math::E, E(N))
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end
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def test_sqrt
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assert_in_delta(2**0.5, sqrt(BigDecimal("2"), N))
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assert_equal(10, sqrt(BigDecimal("100"), N))
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assert_equal(0.0, sqrt(BigDecimal("0"), N))
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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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end
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def test_sin
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assert_in_delta(0.0, sin(BigDecimal("0.0"), N))
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assert_in_delta(Math.sqrt(2.0) / 2, sin(PI(N) / 4, N))
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assert_in_delta(1.0, sin(PI(N) / 2, N))
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assert_in_delta(0.0, sin(PI(N) * 2, N))
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assert_in_delta(0.0, sin(PI(N), N))
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assert_in_delta(-1.0, sin(PI(N) / -2, N))
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assert_in_delta(0.0, sin(PI(N) * -2, N))
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assert_in_delta(0.0, sin(-PI(N), N))
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assert_in_delta(0.0, sin(PI(N) * 21, N))
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assert_in_delta(0.0, sin(PI(N) * 30, N))
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assert_in_delta(-1.0, sin(PI(N) * BigDecimal("301.5"), N))
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end
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def test_cos
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assert_in_delta(1.0, cos(BigDecimal("0.0"), N))
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assert_in_delta(Math.sqrt(2.0) / 2, cos(PI(N) / 4, N))
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assert_in_delta(0.0, cos(PI(N) / 2, N))
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assert_in_delta(1.0, cos(PI(N) * 2, N))
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assert_in_delta(-1.0, cos(PI(N), N))
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assert_in_delta(0.0, cos(PI(N) / -2, N))
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assert_in_delta(1.0, cos(PI(N) * -2, N))
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assert_in_delta(-1.0, cos(-PI(N), N))
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assert_in_delta(-1.0, cos(PI(N) * 21, N))
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assert_in_delta(1.0, cos(PI(N) * 30, N))
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assert_in_delta(0.0, cos(PI(N) * BigDecimal("301.5"), N))
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end
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def test_atan
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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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end
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def test_exp
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assert_in_epsilon(Math::E, exp(BigDecimal("1"), N))
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assert_in_epsilon(Math.exp(N), exp(BigDecimal("20"), N))
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assert_in_epsilon(Math.exp(40), exp(BigDecimal("40"), N))
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assert_in_epsilon(Math.exp(-N), exp(BigDecimal("-20"), N))
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assert_in_epsilon(Math.exp(-40), exp(BigDecimal("-40"), N))
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end
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def test_log
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assert_in_delta(0.0, log(BigDecimal("1"), N))
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assert_in_delta(1.0, log(E(N), N))
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assert_in_delta(Math.log(2.0), log(BigDecimal("2"), N))
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assert_in_delta(2.0, log(E(N)*E(N), N))
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assert_in_delta(Math.log(42.0), log(BigDecimal("42"), N))
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assert_in_delta(Math.log(1e-42), log(BigDecimal("1e-42"), N))
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end
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end
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@ -1,5 +1,5 @@
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#define RUBY_VERSION "1.9.2"
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#define RUBY_RELEASE_DATE "2009-09-20"
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#define RUBY_RELEASE_DATE "2009-09-21"
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#define RUBY_PATCHLEVEL -1
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#define RUBY_BRANCH_NAME "trunk"
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@ -8,7 +8,7 @@
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#define RUBY_VERSION_TEENY 1
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#define RUBY_RELEASE_YEAR 2009
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#define RUBY_RELEASE_MONTH 9
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#define RUBY_RELEASE_DAY 20
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#define RUBY_RELEASE_DAY 21
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#include "ruby/version.h"
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