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