72 lines
1.9 KiB
C++
72 lines
1.9 KiB
C++
// (C) Copyright John Maddock 2014.
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// Use, modification and distribution are subject to the
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// Boost Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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#ifndef BOOST_MATH_TOOLS_MP_T
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#define BOOST_MATH_TOOLS_MP_T
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#ifndef BOOST_MATH_PRECISION
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#define BOOST_MATH_PRECISION 1000
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#endif
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#if defined(BOOST_MATH_USE_MPFR)
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#include <boost/multiprecision/mpfr.hpp>
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typedef boost::multiprecision::number<boost::multiprecision::mpfr_float_backend<BOOST_MATH_PRECISION *301L / 1000L> > mp_t;
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#else
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#include <boost/multiprecision/cpp_bin_float.hpp>
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typedef boost::multiprecision::number<boost::multiprecision::cpp_bin_float<BOOST_MATH_PRECISION, boost::multiprecision::digit_base_2> > mp_t;
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#endif
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inline mp_t ConvPrec(mp_t arg, int digits)
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{
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int e1, e2;
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mp_t t = frexp(arg, &e1);
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t = frexp(floor(ldexp(t, digits + 1)), &e2);
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return ldexp(t, e1);
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}
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inline mp_t relative_error(mp_t a, mp_t b)
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{
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mp_t min_val = boost::math::tools::min_value<mp_t>();
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mp_t max_val = boost::math::tools::max_value<mp_t>();
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if((a != 0) && (b != 0))
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{
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// mp_tODO: use isfinite:
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if(fabs(b) >= max_val)
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{
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if(fabs(a) >= max_val)
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return 0; // one infinity is as good as another!
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}
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// If the result is denormalised, treat all denorms as equivalent:
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if((a < min_val) && (a > 0))
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a = min_val;
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else if((a > -min_val) && (a < 0))
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a = -min_val;
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if((b < min_val) && (b > 0))
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b = min_val;
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else if((b > -min_val) && (b < 0))
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b = -min_val;
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return (std::max)(fabs((a - b) / a), fabs((a - b) / b));
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}
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// Handle special case where one or both are zero:
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if(min_val == 0)
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return fabs(a - b);
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if(fabs(a) < min_val)
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a = min_val;
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if(fabs(b) < min_val)
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b = min_val;
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return (std::max)(fabs((a - b) / a), fabs((a - b) / b));
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}
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#endif // BOOST_MATH_TOOLS_MP_T
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