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authornobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2017-02-24 08:36:16 (GMT)
committernobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>2017-02-24 08:36:16 (GMT)
commitbdd6b995f91277a258db8614371be08e3fe9988d (patch)
tree9bd730f01373ca5ebf32160f2da0382121bde394 /numeric.c
parent395ad27e7235bf32d89e747507f7f1518d5aa844 (diff)
Integer.sqrt [Feature #13219]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57705 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'numeric.c')
-rw-r--r--numeric.c59
1 files changed, 59 insertions, 0 deletions
diff --git a/numeric.c b/numeric.c
index 16cdbb2..2784b6d 100644
--- a/numeric.c
+++ b/numeric.c
@@ -5128,6 +5128,64 @@ int_truncate(int argc, VALUE* argv, VALUE num)
return rb_int_truncate(num, ndigits);
}
+#define DEFINE_INT_SQRT(rettype, prefix, argtype) \
+rettype \
+prefix##_isqrt(argtype n) \
+{ \
+ if (sizeof(n) * CHAR_BIT > DBL_MANT_DIG && \
+ n >= ((argtype)1UL << DBL_MANT_DIG)) { \
+ unsigned int b = bit_length(n); \
+ argtype t; \
+ rettype x = (rettype)(n >> (b/2+1)); \
+ x |= ((rettype)1LU << (b-1)/2); \
+ while ((t = n/x) < (argtype)x) x = (rettype)((x + t) >> 1); \
+ return x; \
+ } \
+ return (rettype)sqrt((double)n); \
+}
+
+DEFINE_INT_SQRT(unsigned long, rb_ulong, unsigned long)
+#if SIZEOF_BDIGIT*2 > SIZEOF_LONG
+DEFINE_INT_SQRT(BDIGIT, rb_bdigit_dbl, BDIGIT_DBL)
+#endif
+
+#define domain_error(msg) \
+ rb_raise(rb_eMathDomainError, "Numerical argument is out of domain - " #msg)
+
+VALUE rb_big_isqrt(VALUE);
+
+static VALUE
+rb_int_s_isqrt(VALUE self, VALUE num)
+{
+ unsigned long n, sq;
+ if (FIXNUM_P(num)) {
+ if (FIXNUM_NEGATIVE_P(num)) {
+ domain_error("isqrt");
+ }
+ n = FIX2ULONG(num);
+ sq = rb_ulong_isqrt(n);
+ return LONG2FIX(sq);
+ }
+ if (RB_TYPE_P(num, T_BIGNUM)) {
+ size_t biglen;
+ if (RBIGNUM_NEGATIVE_P(num)) {
+ domain_error("isqrt");
+ }
+ biglen = BIGNUM_LEN(num);
+ if (biglen == 0) return INT2FIX(0);
+#if SIZEOF_BDIGIT <= SIZEOF_LONG
+ /* short-circuit */
+ if (biglen == 1) {
+ n = BIGNUM_DIGITS(num)[0];
+ sq = rb_ulong_isqrt(n);
+ return ULONG2NUM(sq);
+ }
+#endif
+ return rb_big_isqrt(num);
+ }
+ return Qnil;
+}
+
/*
* Document-class: ZeroDivisionError
*
@@ -5281,6 +5339,7 @@ Init_Numeric(void)
rb_cInteger = rb_define_class("Integer", rb_cNumeric);
rb_undef_alloc_func(rb_cInteger);
rb_undef_method(CLASS_OF(rb_cInteger), "new");
+ rb_define_singleton_method(rb_cInteger, "sqrt", rb_int_s_isqrt, 1);
rb_define_method(rb_cInteger, "to_s", int_to_s, -1);
rb_define_alias(rb_cInteger, "inspect", "to_s");