ceph/src/boost/libs/multiprecision/test/test_rat_float_interconv.cpp

   1 // Copyright John Maddock 2013.
   2
   3 // Use, modification and distribution are subject to the
   4 // Boost Software License, Version 1.0.
   5 // (See accompanying file LICENSE_1_0.txt
   6 // or copy at http://www.boost.org/LICENSE_1_0.txt)
   7
   8 #ifdef _MSC_VER
   9 #  define _SCL_SECURE_NO_WARNINGS
  10 #endif
  11
  12 #if defined(TEST1) || defined(TEST2) || defined(TEST3) || defined(TEST4)
  13 #include <boost/multiprecision/cpp_bin_float.hpp>
  14 #include <boost/multiprecision/cpp_int.hpp>
  15 #else
  16 #include <boost/multiprecision/mpfr.hpp>
  17 #endif
  18 #include <boost/math/special_functions/next.hpp>
  19
  20 #include <boost/random/mersenne_twister.hpp>
  21 #include <boost/random/uniform_int.hpp>
  22 #include <boost/chrono.hpp>
  23 #include "test.hpp"
  24 #include <boost/array.hpp>
  25 #include <iostream>
  26 #include <iomanip>
  27
  28 #ifdef BOOST_MSVC
  29 #pragma warning(disable:4127)
  30 #endif
  31
  32 template <class Clock>
  33 struct stopwatch
  34 {
  35    typedef typename Clock::duration duration;
  36    stopwatch()
  37    {
  38       m_start = Clock::now();
  39    }
  40    duration elapsed()
  41    {
  42       return Clock::now() - m_start;
  43    }
  44    void reset()
  45    {
  46       m_start = Clock::now();
  47    }
  48
  49 private:
  50    typename Clock::time_point m_start;
  51 };
  52
  53 template <class T>
  54 struct exponent_type
  55 {
  56    typedef int type;
  57 };
  58 template <class T, boost::multiprecision::expression_template_option ET>
  59 struct exponent_type<boost::multiprecision::number<T, ET> >
  60 {
  61    typedef typename T::exponent_type type;
  62 };
  63
  64 template <class T>
  65 T generate_random_float()
  66 {
  67    BOOST_MATH_STD_USING
  68    typedef typename exponent_type<T>::type e_type;
  69    static boost::random::mt19937 gen;
  70    T val = gen();
  71    T prev_val = -1;
  72    while(val != prev_val)
  73    {
  74       val *= (gen.max)();
  75       prev_val = val;
  76       val += gen();
  77    }
  78    e_type e;
  79    val = frexp(val, &e);
  80
  81    static const int max_exponent_value = (std::min)(static_cast<int>(std::numeric_limits<T>::max_exponent - std::numeric_limits<T>::digits - 20), 2000);
  82    static boost::random::uniform_int_distribution<e_type> ui(0, max_exponent_value);
  83    return ldexp(val, ui(gen));
  84 }
  85
  86 template <class Float, class Rat>
  87 void do_round_trip(const Float& val)
  88 {
  89 #ifndef BOOST_MP_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS
  90    BOOST_MATH_STD_USING
  91    Rat rat(val);
  92    Float new_f(rat);
  93    BOOST_CHECK_EQUAL(val, new_f);
  94    //
  95    // Try adding or subtracting an insignificant amount
  96    // (0.25ulp) from rat and check that it rounds to the same value:
  97    //
  98    typename exponent_type<Float>::type e;
  99    Float t = frexp(val, &e);
 100    (void)t; // warning suppression
 101    e -= std::numeric_limits<Float>::digits + 2;
 102    BOOST_ASSERT(val == (val + ldexp(Float(1), e)));
 103    Rat delta, rounded;
 104    typedef typename boost::multiprecision::component_type<Rat>::type i_type;
 105    i_type i(1);
 106    i <<= (e < 0 ? -e : e);
 107    if(e > 0)
 108       delta.assign(i);
 109    else
 110       delta = Rat(i_type(1), i);
 111    rounded = rat + delta;
 112    new_f = static_cast<Float>(rounded);
 113    BOOST_CHECK_EQUAL(val, new_f);
 114    rounded = rat - delta;
 115    new_f = static_cast<Float>(rounded);
 116    BOOST_CHECK_EQUAL(val, new_f);
 117
 118    delta /= 2;
 119    rounded = rat + delta;
 120    new_f = static_cast<Float>(rounded);
 121    BOOST_CHECK_EQUAL(val, new_f);
 122    rounded = rat - delta;
 123    new_f = static_cast<Float>(rounded);
 124    BOOST_CHECK_EQUAL(val, new_f);
 125
 126    delta /= 2;
 127    rounded = rat + delta;
 128    new_f = static_cast<Float>(rounded);
 129    BOOST_CHECK_EQUAL(val, new_f);
 130    rounded = rat - delta;
 131    new_f = static_cast<Float>(rounded);
 132    BOOST_CHECK_EQUAL(val, new_f);
 133 #endif
 134 }
 135
 136 template <class Float, class Rat>
 137 void test_round_trip()
 138 {
 139 #ifndef BOOST_MP_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS
 140    std::cout << "Testing types " << typeid(Float).name() << " <<==>> " << typeid(Rat).name() << std::endl;
 141    std::cout << "digits = " << std::numeric_limits<Float>::digits << std::endl;
 142    std::cout << "digits10 = " << std::numeric_limits<Float>::digits10 << std::endl;
 143 #ifndef BOOST_NO_CXX11_NUMERIC_LIMITS
 144    std::cout << "max_digits10 = " << std::numeric_limits<Float>::max_digits10 << std::endl;
 145 #endif
 146
 147    stopwatch<boost::chrono::high_resolution_clock> w;
 148
 149    int count = 0;
 150
 151    while(boost::chrono::duration_cast<boost::chrono::duration<double> >(w.elapsed()).count() < 200)
 152    {
 153       Float val = generate_random_float<Float>();
 154       do_round_trip<Float, Rat>(val);
 155       do_round_trip<Float, Rat>(Float(-val));
 156       do_round_trip<Float, Rat>(Float(1/val));
 157       do_round_trip<Float, Rat>(Float(-1/val));
 158       count += 4;
 159       if(boost::detail::test_errors() > 100)
 160          break;
 161    }
 162
 163    std::cout << "Execution time = " << boost::chrono::duration_cast<boost::chrono::duration<double> >(w.elapsed()).count() << "s" << std::endl;
 164    std::cout << "Total values tested: " << count << std::endl;
 165 #endif
 166 }
 167
 168 template <class Int>
 169 Int generate_random_int()
 170 {
 171    static boost::random::mt19937 gen;
 172    static boost::random::uniform_int_distribution<boost::random::mt19937::result_type> d(1, 20);
 173
 174    int lim;
 175    Int cppi(0);
 176
 177    lim = d(gen);
 178
 179    for(int i = 0; i < lim; ++i)
 180    {
 181       cppi *= (gen.max)();
 182       cppi += gen();
 183    }
 184    return cppi;
 185 }
 186
 187 template <class Float, class Rat>
 188 void test_random_rationals()
 189 {
 190 #ifndef BOOST_MP_NO_CXX11_EXPLICIT_CONVERSION_OPERATORS
 191    std::cout << "Testing types " << typeid(Float).name() << " <<==>> " << typeid(Rat).name() << std::endl;
 192    std::cout << "digits = " << std::numeric_limits<Float>::digits << std::endl;
 193    std::cout << "digits10 = " << std::numeric_limits<Float>::digits10 << std::endl;
 194 #ifndef BOOST_NO_CXX11_NUMERIC_LIMITS
 195    std::cout << "max_digits10 = " << std::numeric_limits<Float>::max_digits10 << std::endl;
 196 #endif
 197
 198    typedef typename boost::multiprecision::component_type<Rat>::type i_type;
 199    stopwatch<boost::chrono::high_resolution_clock> w;
 200
 201    int count = 0;
 202
 203    while(boost::chrono::duration_cast<boost::chrono::duration<double> >(w.elapsed()).count() < 200)
 204    {
 205       Rat rat(generate_random_int<i_type>(), generate_random_int<i_type>());
 206       Float f(rat);
 207       Rat new_rat(f); // rounded value
 208       int c = new_rat.compare(rat);
 209       if(c < 0)
 210       {
 211          // If f was rounded down, next float up must be above the original value:
 212          f = boost::math::float_next(f);
 213          new_rat.assign(f);
 214          BOOST_CHECK(new_rat >= rat);
 215       }
 216       else if(c > 0)
 217       {
 218          // If f was rounded up, next float down must be below the original value:
 219          f = boost::math::float_prior(f);
 220          new_rat.assign(f);
 221          BOOST_CHECK(new_rat <= rat);
 222       }
 223       else
 224       {
 225          // Values were equal... nothing to test.
 226       }
 227       if(boost::detail::test_errors() > 100)
 228          break;
 229    }
 230
 231    std::cout << "Execution time = " << boost::chrono::duration_cast<boost::chrono::duration<double> >(w.elapsed()).count() << "s" << std::endl;
 232    std::cout << "Total values tested: " << count << std::endl;
 233 #endif
 234 }
 235
 236 #if defined(TEST2)
 237
 238 void double_spot_tests()
 239 {
 240    boost::multiprecision::cpp_rational rat = 1;
 241    boost::multiprecision::cpp_rational twiddle(boost::multiprecision::cpp_int(1), boost::multiprecision::cpp_int(boost::multiprecision::cpp_int(1) << 54));
 242    rat += boost::multiprecision::cpp_rational(boost::multiprecision::cpp_int(1), boost::multiprecision::cpp_int(boost::multiprecision::cpp_int(1) << 50));
 243
 244    double d = rat.convert_to<double>();
 245
 246    rat += twiddle;
 247    BOOST_CHECK_EQUAL(d, rat.convert_to<double>());
 248    rat += twiddle;
 249    // tie: round to even rounds down
 250    BOOST_CHECK_EQUAL(d, rat.convert_to<double>());
 251    rat += twiddle;
 252    BOOST_CHECK_NE(d, rat.convert_to<double>());
 253    rat -= twiddle;
 254    BOOST_CHECK_EQUAL(d, rat.convert_to<double>());
 255    rat += boost::multiprecision::cpp_rational(boost::multiprecision::cpp_int(1), boost::multiprecision::cpp_int(boost::multiprecision::cpp_int(1) << 52));
 256    // tie, but last bit is now a 1 so we round up:
 257    BOOST_CHECK_NE(d, rat.convert_to<double>());
 258
 259 }
 260
 261 #endif
 262
 263 int main()
 264 {
 265    using namespace boost::multiprecision;
 266 #if defined(TEST1) && !defined(BOOST_MSVC)
 267    test_round_trip<number<cpp_bin_float<113, digit_base_2, void, boost::int16_t> >, cpp_rational>();
 268 #elif defined(TEST2)
 269    double_spot_tests();
 270    test_round_trip<double, cpp_rational>();
 271 #elif defined(TEST3) && !defined(BOOST_MSVC)
 272    test_random_rationals<number<cpp_bin_float<113, digit_base_2, void, boost::int16_t> >, cpp_rational>();
 273 #elif defined(TEST4)
 274    test_random_rationals<double, cpp_rational>();
 275 #elif defined(TEST5)
 276    // This does not work: gmp does not correctly round integer to float or
 277    // rational to float conversions:
 278    test_round_trip<double, mpq_rational>();
 279 #elif defined(TEST6)
 280    test_round_trip<mpfr_float_100, mpq_rational>();
 281 #elif defined(TEST7)
 282    test_random_rationals<mpfr_float_100, mpq_rational>();
 283 #elif defined(TEST8)
 284    test_random_rationals<double, mpq_rational>();
 285 #endif
 286    return boost::report_errors();
 287 }
 288