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* numeric.c (fix_pow): integer power calculation: 0**n => 0,

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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.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12789 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
matz 2007-07-14 14:31:21 +00:00
parent bb44ba9b72
commit 7f0bb427e0
3 changed files with 29 additions and 6 deletions
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8
ChangeLog
View file

@ -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> Sat Jul 14 18:46:35 2007 Tanaka Akira <akr@fsij.org>
* configure.in: add --with-valgrind. * configure.in: add --with-valgrind.

25
numeric.c
View file

@ -2326,14 +2326,21 @@ int_pow(long x, unsigned long y)
static VALUE static VALUE
fix_pow(VALUE x, VALUE y) fix_pow(VALUE x, VALUE y)
{ {
if (FIXNUM_P(y)) { long a = FIX2LONG(x);
long a, b;
if (FIXNUM_P(y)) {
long b = FIX2LONG(y);
b = FIX2LONG(y);
if (b == 0) return INT2FIX(1); if (b == 0) return INT2FIX(1);
if (b == 1) return x; if (b == 1) return x;
a = FIX2LONG(x);
if (a == 0) return INT2FIX(0); 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) { if (b > 0) {
return int_pow(a, b); return int_pow(a, b);
} }
@ -2341,10 +2348,18 @@ fix_pow(VALUE x, VALUE y)
} }
switch (TYPE(y)) { switch (TYPE(y)) {
case T_BIGNUM: 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)); x = rb_int2big(FIX2LONG(x));
return rb_big_pow(x, y); return rb_big_pow(x, y);
case T_FLOAT: 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: default:
return rb_num_coerce_bin(x, y); return rb_num_coerce_bin(x, y);
} }

2
test/ruby/test_fixnum.rb
View file

@ -12,7 +12,7 @@ class TestFixnum < Test::Unit::TestCase
def test_pow def test_pow
[1, 2, 2**64, 2**63*3, 2**64*3].each do |y| [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 z1 = x**y
z2 = (-x)**y z2 = (-x)**y
if y % 2 == 1 if y % 2 == 1