120 lines
4.2 KiB
C++
120 lines
4.2 KiB
C++
///////////////////////////////////////////////////////////////
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// Copyright 2013 John Maddock. Distributed under the Boost
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// Software License, Version 1.0. (See accompanying file
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// LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt
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//[logged_adaptor
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#include <boost/multiprecision/mpfi.hpp>
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#include <boost/multiprecision/logged_adaptor.hpp>
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#include <iostream>
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#include <iomanip>
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//
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// Begin by overloading log_postfix_event so we can capture each arithmetic event as it happens:
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//
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namespace boost{ namespace multiprecision{
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template <unsigned D>
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inline void log_postfix_event(const mpfi_float_backend<D>& val, const char* event_description)
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{
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// Print out the (relative) diameter of the interval:
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using namespace boost::multiprecision;
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number<mpfr_float_backend<D> > diam;
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mpfi_diam(diam.backend().data(), val.data());
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std::cout << "Diameter was " << diam << " after operation: " << event_description << std::endl;
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}
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template <unsigned D, class T>
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inline void log_postfix_event(const mpfi_float_backend<D>&, const T&, const char* event_description)
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{
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// This version is never called in this example.
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}
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}}
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int main()
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{
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using namespace boost::multiprecision;
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typedef number<logged_adaptor<mpfi_float_backend<17> > > logged_type;
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//
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// Test case deliberately introduces cancellation error, relative size of interval
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// gradually gets larger after each operation:
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//
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logged_type a = 1;
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a /= 10;
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for(unsigned i = 0; i < 13; ++i)
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{
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logged_type b = a * 9;
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b /= 10;
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a -= b;
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}
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std::cout << "Final value was: " << a << std::endl;
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return 0;
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}
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//]
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/*
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//[logged_adaptor_output
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Diameter was nan after operation: Default construct
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Diameter was 0 after operation: Assignment from arithmetic type
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Diameter was 4.33681e-18 after operation: /=
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Diameter was nan after operation: Default construct
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Diameter was 7.70988e-18 after operation: *
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Diameter was 9.63735e-18 after operation: /=
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Diameter was 1.30104e-16 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 1.30104e-16 after operation: *
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Diameter was 1.38537e-16 after operation: /=
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Diameter was 2.54788e-15 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 2.54788e-15 after operation: *
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Diameter was 2.54863e-15 after operation: /=
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Diameter was 4.84164e-14 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 4.84164e-14 after operation: *
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Diameter was 4.84221e-14 after operation: /=
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Diameter was 9.19962e-13 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 9.19962e-13 after operation: *
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Diameter was 9.19966e-13 after operation: /=
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Diameter was 1.74793e-11 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 1.74793e-11 after operation: *
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Diameter was 1.74793e-11 after operation: /=
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Diameter was 3.32107e-10 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 3.32107e-10 after operation: *
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Diameter was 3.32107e-10 after operation: /=
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Diameter was 6.31003e-09 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 6.31003e-09 after operation: *
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Diameter was 6.31003e-09 after operation: /=
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Diameter was 1.19891e-07 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 1.19891e-07 after operation: *
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Diameter was 1.19891e-07 after operation: /=
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Diameter was 2.27792e-06 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 2.27792e-06 after operation: *
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Diameter was 2.27792e-06 after operation: /=
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Diameter was 4.32805e-05 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 4.32805e-05 after operation: *
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Diameter was 4.32805e-05 after operation: /=
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Diameter was 0.00082233 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 0.00082233 after operation: *
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Diameter was 0.00082233 after operation: /=
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Diameter was 0.0156243 after operation: -=
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Diameter was nan after operation: Default construct
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Diameter was 0.0156243 after operation: *
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Diameter was 0.0156243 after operation: /=
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Diameter was 0.296861 after operation: -=
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Final value was: {8.51569e-15,1.14843e-14}
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//]
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*/
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