diff options
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | numeric.c | 23 | ||||
| -rw-r--r-- | test/ruby/test_fixnum.rb | 2 |
3 files changed, 28 insertions, 5 deletions
@@ -1,3 +1,11 @@ +Sat Jul 14 22:49:30 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. + Sat Jul 14 18:46:35 2007 Tanaka Akira <akr@fsij.org> * configure.in: add --with-valgrind. @@ -2326,14 +2326,21 @@ int_pow(long x, unsigned long y) static VALUE fix_pow(VALUE x, VALUE y) { + long a = FIX2LONG(x); + if (FIXNUM_P(y)) { - long a, b; + long b = FIX2LONG(y); - 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); } @@ -2341,10 +2348,18 @@ fix_pow(VALUE x, VALUE 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: - return rb_float_new(pow((double)FIX2LONG(x), RFLOAT(y)->value)); + 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 13281ca0e..81a091eb4 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 |