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Merge branch 'develop' of https://github.com/boostorg/multiprecision into develop

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This commit is contained in:
John Maddock
2016-07-26 16:57:34 +00:00
parent 3d18f5002f 7ebd9dfd9b
commit 0492ba22bb
2 changed files with 31 additions and 3 deletions
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6
include/boost/multiprecision/detail/generic_interconvert.hpp
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@@ -310,7 +310,7 @@ typename enable_if_c<is_number<To>::value || is_floating_point<To>::value>::type
num = -num;
}
int denom_bits = msb(denom);
int shift = std::numeric_limits<To>::digits + denom_bits - msb(num) + 1;
int shift = std::numeric_limits<To>::digits + denom_bits - msb(num);
if(shift > 0)
num <<= shift;
else if(shift < 0)
@@ -318,7 +318,7 @@ typename enable_if_c<is_number<To>::value || is_floating_point<To>::value>::type
Integer q, r;
divide_qr(num, denom, q, r);
int q_bits = msb(q);
if(q_bits == std::numeric_limits<To>::digits)
if(q_bits == std::numeric_limits<To>::digits - 1)
{
//
// Round up if 2 * r > denom:
@@ -334,7 +334,7 @@ typename enable_if_c<is_number<To>::value || is_floating_point<To>::value>::type
}
else
{
BOOST_ASSERT(q_bits == 1 + std::numeric_limits<To>::digits);
BOOST_ASSERT(q_bits == std::numeric_limits<To>::digits);
//
// We basically already have the rounding info:
//

28
test/test_rat_float_interconv.cpp
View File

@@ -233,12 +233,40 @@ void test_random_rationals()
#endif
}
#if defined(TEST2)
void double_spot_tests()
{
boost::multiprecision::cpp_rational rat = 1;
boost::multiprecision::cpp_rational twiddle(boost::multiprecision::cpp_int(1), boost::multiprecision::cpp_int(boost::multiprecision::cpp_int(1) << 54));
rat += boost::multiprecision::cpp_rational(boost::multiprecision::cpp_int(1), boost::multiprecision::cpp_int(boost::multiprecision::cpp_int(1) << 50));
double d = rat.convert_to<double>();
rat += twiddle;
BOOST_CHECK_EQUAL(d, rat.convert_to<double>());
rat += twiddle;
// tie: round to even rounds down
BOOST_CHECK_EQUAL(d, rat.convert_to<double>());
rat += twiddle;
BOOST_CHECK_NE(d, rat.convert_to<double>());
rat -= twiddle;
BOOST_CHECK_EQUAL(d, rat.convert_to<double>());
rat += boost::multiprecision::cpp_rational(boost::multiprecision::cpp_int(1), boost::multiprecision::cpp_int(boost::multiprecision::cpp_int(1) << 52));
// tie, but last bit is now a 1 so we round up:
BOOST_CHECK_NE(d, rat.convert_to<double>());
}
#endif
int main()
{
using namespace boost::multiprecision;
#if defined(TEST1) && !defined(BOOST_MSVC)
test_round_trip<number<cpp_bin_float<113, digit_base_2, void, boost::int16_t> >, cpp_rational>();
#elif defined(TEST2)
double_spot_tests();
test_round_trip<double, cpp_rational>();
#elif defined(TEST3) && !defined(BOOST_MSVC)
test_random_rationals<number<cpp_bin_float<113, digit_base_2, void, boost::int16_t> >, cpp_rational>();