diff options
author | matz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2007-07-14 14:31:21 +0000 |
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committer | matz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2007-07-14 14:31:21 +0000 |
commit | 7f0bb427e09ab985da52217f792c292ba9d0c556 (patch) | |
tree | 8c819ec7470696280d10f72a832d7f3f6e1b0a55 /numeric.c | |
parent | bb44ba9b72adf41dc17714351df724bc5c21bd7a (diff) |
* 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.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12789 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'numeric.c')
-rw-r--r-- | numeric.c | 23 |
1 files changed, 19 insertions, 4 deletions
@@ -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); } |