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Implement floor() and ceil() for rational types. #214

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Implement floor() and ceil() for rational types. #214

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20 changes: 20 additions & 0 deletions include/boost/multiprecision/rational_adaptor.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -318,6 +318,26 @@ inline number<IntBackend, ET> denominator(const number<rational_adaptor<IntBacke
{
return val.backend().data().denominator();
}
template <class IntBackend, expression_template_option ET>
inline number<IntBackend, ET> floor(const number<rational_adaptor<IntBackend>, ET>& val)
{
// Here we use the assumption that denominator is always positive
// and numerator has the sign
if (val >= 0)
return numerator(val) / denominator(val);
else
return (numerator(val) + 1) / denominator(val) - 1;
}
template <class IntBackend, expression_template_option ET>
inline number<IntBackend, ET> ceil(const number<rational_adaptor<IntBackend>, ET>& val)
{
// Here we use the assumption that denominator is always positive
// and numerator has the sign
if (val >= 0)
return (numerator(val) - 1) / denominator(val) + 1;
else
return numerator(val) / denominator(val);
}

#ifdef BOOST_NO_SFINAE_EXPR

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11 changes: 11 additions & 0 deletions test/test_arithmetic.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -293,6 +293,17 @@ void test_rational(const boost::mpl::false_&)
#endif
b = Real("2/3");
BOOST_CHECK_EQUAL(a, b);

const static int floor_ceil_data[][4] = {{-11, 10, -2, -1}, {-10, 10, -1, -1}, {-9, 10, -1, 0},
{-1, 10, -1, 0}, {0, 10, 0, 0}, {1, 10, 0, 1},
{9, 10, 0, 1}, {10, 10, 1, 1}, {11, 10, 1, 2}};
for (unsigned int i = 0; i < sizeof(floor_ceil_data) / sizeof(floor_ceil_data[0]); i++) {
Real c(floor_ceil_data[i][0]);
c /= floor_ceil_data[i][1];
BOOST_CHECK_EQUAL(floor(c), floor_ceil_data[i][2]);
BOOST_CHECK_EQUAL(ceil(c), floor_ceil_data[i][3]);
}

//
// Check IO code:
//
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