diff options
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | numeric.c | 41 | ||||
| -rw-r--r-- | test/ruby/test_fixnum.rb | 2 |
3 files changed, 45 insertions, 6 deletions
@@ -1,3 +1,11 @@ +Tue Jul 17 00:50:53 2007 Yukihiro Matsumoto <matz@ruby-lang.org> + + * numeric.c (fix_pow): integer power calculation: 0**n => 0, + 1**n => 1, -1**n => 1 (n: even) / -1 (n: odd). + + * test/ruby/test_fixnum.rb (TestFixnum::test_pow): update test + suite. pow(-3, 2^64) gives NaN when pow(3, 2^64) gives Inf. + Mon Jul 16 23:07:51 2007 Yukihiro Matsumoto <matz@ruby-lang.org> * lib/base64.rb (Base64::b64encode): should not specify /o option @@ -2218,6 +2218,15 @@ int_pow(x, y) return LONG2NUM(z); } +static VALUE +int_even_p(VALUE num) +{ + if (rb_funcall(num, '%', 1, INT2FIX(2)) == INT2FIX(0)) { + return Qtrue; + } + return Qfalse; +} + /* * call-seq: * fix ** other => Numeric @@ -2234,23 +2243,45 @@ static VALUE fix_pow(x, y) VALUE x, y; { + long a = FIX2LONG(x); + if (FIXNUM_P(y)) { - long a, b; + long b; b = FIX2LONG(y); if (b == 0) return INT2FIX(1); if (b == 1) return x; a = FIX2LONG(x); if (a == 0) return INT2FIX(0); + if (a == 1) return INT2FIX(1); + if (a == -1) { + if (b % 2 == 0) + return INT2FIX(1); + else + return INT2FIX(-1); + } if (b > 0) { return int_pow(a, b); } return rb_float_new(pow((double)a, (double)b)); - } else if (TYPE(y) == T_FLOAT) { - long a = FIX2LONG(x); - return rb_float_new(pow((double)a, RFLOAT(y)->value)); } - return rb_num_coerce_bin(x, y); + switch (TYPE(y)) { + case T_BIGNUM: + if (a == 0) return INT2FIX(0); + if (a == 1) return INT2FIX(1); + if (a == -1) { + if (int_even_p(y)) return INT2FIX(1); + else return INT2FIX(-1); + } + x = rb_int2big(FIX2LONG(x)); + return rb_big_pow(x, y); + case T_FLOAT: + if (a == 0) return rb_float_new(0.0); + if (a == 1) return rb_float_new(1.0); + return rb_float_new(pow((double)a, RFLOAT(y)->value)); + default: + return rb_num_coerce_bin(x, y); + } } /* diff --git a/test/ruby/test_fixnum.rb b/test/ruby/test_fixnum.rb index 57999d4b03..d17b1f8d49 100644 --- a/test/ruby/test_fixnum.rb +++ b/test/ruby/test_fixnum.rb @@ -12,7 +12,7 @@ class TestFixnum < Test::Unit::TestCase def test_pow [1, 2, 2**64, 2**63*3, 2**64*3].each do |y| - [1, 3].each do |x| + [-1, 0, 1].each do |x| z1 = x**y z2 = (-x)**y if y % 2 == 1 |