diff options
| -rw-r--r-- | ChangeLog | 5 | ||||
| -rw-r--r-- | ext/bigdecimal/lib/bigdecimal/math.rb | 20 | ||||
| -rw-r--r-- | test/bigdecimal/test_bigmath.rb | 3 |
3 files changed, 13 insertions, 15 deletions
@@ -1,4 +1,7 @@ -Thu Sep 24 02:08:35 2009 Nobuyoshi Nakada <nobu@ruby-lang.org> +Thu Sep 24 02:21:23 2009 Nobuyoshi Nakada <nobu@ruby-lang.org> + + * ext/bigdecimal/lib/bigdecimal/math.rb (atan): atan(Infinity) is + PI/2. * ext/bigdecimal/lib/bigdecimal/math.rb (atan): reduce loop with the formula of the double corner. based on a patch from diff --git a/ext/bigdecimal/lib/bigdecimal/math.rb b/ext/bigdecimal/lib/bigdecimal/math.rb index d1e8dbe326..eeffde4e68 100644 --- a/ext/bigdecimal/lib/bigdecimal/math.rb +++ b/ext/bigdecimal/lib/bigdecimal/math.rb @@ -117,22 +117,16 @@ module BigMath # Computes the arctangent of x to the specified number of digits of precision. # - # If x is infinite or NaN, returns NaN. + # If x is NaN, returns NaN. def atan(x, prec) raise ArgumentError, "Zero or negative precision for atan" if prec <= 0 - return BigDecimal("NaN") if x.infinite? || x.nan? + return BigDecimal("NaN") if x.nan? pi = PI(prec) - if neg = x < 0 - x = -x - end - if x.round(prec) == 1 - return pi / (neg ? -4 : 4) - elsif inv = x > 1 - x = 1 / x - end - if dbl = x > 0.5 - x = (-1 + sqrt(1 + x**2, prec))/x - end + x = -x if neg = x < 0 + return pi.div(neg ? -2 : 2, prec) if x.infinite? + return pi / (neg ? -4 : 4) if x.round(prec) == 1 + x = 1 / x if inv = x > 1 + x = (-1 + sqrt(1 + x**2, prec))/x if dbl = x > 0.5 n = prec + BigDecimal.double_fig y = x d = y diff --git a/test/bigdecimal/test_bigmath.rb b/test/bigdecimal/test_bigmath.rb index 7801e6045b..2870664bcf 100644 --- a/test/bigdecimal/test_bigmath.rb +++ b/test/bigdecimal/test_bigmath.rb @@ -21,7 +21,7 @@ class TestBigMath < Test::Unit::TestCase assert_equal(0.0, sqrt(BigDecimal("-0"), N)) assert_raise(FloatDomainError) {sqrt(BigDecimal("-1.0"), N)} assert_raise(FloatDomainError) {sqrt(NAN, N)} - assert_equal(PINF, sqrt(PINF, N)) + assert_raise(FloatDomainError) {sqrt(PINF, N)} end def test_sin @@ -56,6 +56,7 @@ class TestBigMath < Test::Unit::TestCase assert_equal(0.0, atan(BigDecimal("0.0"), N)) assert_in_delta(Math::PI/4, atan(BigDecimal("1.0"), N)) assert_in_delta(Math::PI/6, atan(sqrt(BigDecimal("3.0"), N) / 3, N)) + assert_in_delta(Math::PI/2, atan(PINF, N)) end def test_exp |