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66 lines
2.2 KiB
C++
66 lines
2.2 KiB
C++
///////////////////////////////////////////////////////////////
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// Copyright 2023 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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#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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bool event_has_been_called = false;
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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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event_has_been_called = true;
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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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}
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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 boost::multiprecision::event_has_been_called ? 0 : -1;
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}
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