127 lines
4.6 KiB
C++
127 lines
4.6 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 <iostream>
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#include <iomanip>
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#include <boost/multiprecision/fwd.hpp>
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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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// unfortunately this must occur BEFORE we include the full header, so just include the forward
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// declarations and define our overloads for now. Note that in some cases we may need to just
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// declare the overloads here, and define them once the types become concrete:
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//
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namespace boost {
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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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} // namespace boost::multiprecision
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//
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// Now we can include the actual multiprecision headers and make the types concrete:
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//
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#include <boost/multiprecision/mpfi.hpp>
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#include <boost/multiprecision/logged_adaptor.hpp>
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int main()
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{
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using namespace boost::multiprecision;
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using logged_type = logged_adaptor_t<mpfi_float_50>;
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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 -0 after operation: Default construct
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Diameter was 0 after operation: Assignment from arithmetic type
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Diameter was 3.34096e-51 after operation: /=
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Diameter was -0 after operation: Default construct
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Diameter was 5.93948e-51 after operation: *
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Diameter was 7.42435e-51 after operation: /=
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Diameter was 1.00229e-49 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 1.00229e-49 after operation: *
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Diameter was 1.02085e-49 after operation: /=
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Diameter was 1.92105e-48 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 1.92105e-48 after operation: *
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Diameter was 1.92279e-48 after operation: /=
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Diameter was 3.65156e-47 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 3.65156e-47 after operation: *
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Diameter was 3.65163e-47 after operation: /=
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Diameter was 6.93803e-46 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 6.93803e-46 after operation: *
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Diameter was 6.93803e-46 after operation: /=
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Diameter was 1.31823e-44 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 1.31823e-44 after operation: *
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Diameter was 1.31823e-44 after operation: /=
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Diameter was 2.50463e-43 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 2.50463e-43 after operation: *
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Diameter was 2.50463e-43 after operation: /=
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Diameter was 4.7588e-42 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 4.7588e-42 after operation: *
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Diameter was 4.7588e-42 after operation: /=
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Diameter was 9.04171e-41 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 9.04171e-41 after operation: *
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Diameter was 9.04171e-41 after operation: /=
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Diameter was 1.71793e-39 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 1.71793e-39 after operation: *
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Diameter was 1.71793e-39 after operation: /=
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Diameter was 3.26406e-38 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 3.26406e-38 after operation: *
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Diameter was 3.26406e-38 after operation: /=
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Diameter was 6.20171e-37 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 6.20171e-37 after operation: *
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Diameter was 6.20171e-37 after operation: /=
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Diameter was 1.17832e-35 after operation: -=
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Diameter was -0 after operation: Default construct
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Diameter was 1.17832e-35 after operation: *
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Diameter was 1.17832e-35 after operation: /=
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Diameter was 2.23882e-34 after operation: -=
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Final value was: {1e-14,1e-14}
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//]
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*/
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