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2 years ago
#include <fenv.h>
#include <iomanip>
#include <iostream>
#include <boost/numeric/interval.hpp>
// clang-format off
typedef boost::numeric::interval<
double,
boost::numeric::interval_lib::policies<
boost::numeric::interval_lib::save_state<
boost::numeric::interval_lib::rounded_transc_std<double> >,
boost::numeric::interval_lib::checking_base<double> > >
Interval;
// clang-format on
void show_fe_current_rounding_method(void)
{
switch (fegetround()) {
case FE_TONEAREST:
std::cout << "FE_TONEAREST" << std::endl;
break;
case FE_DOWNWARD:
std::cout << "FE_DOWNWARD" << std::endl;
break;
case FE_UPWARD:
std::cout << "FE_UPWARD" << std::endl;
break;
case FE_TOWARDZERO:
std::cout << "FE_TOWARDZERO" << std::endl;
break;
default:
std::cout << "unknown" << std::endl;
};
}
int main(int argc, char* argv[])
{
{
Interval theta = Interval(0.79358805865013693);
Interval output = cos(theta);
std::cout << std::setprecision(
std::numeric_limits<double>::digits10 + 1)
<< "[" << output.lower() << ", " << output.upper() << "]"
<< std::endl;
std::cout << "is empty: "
<< (output.lower() > output.upper() ? "true" : "false")
<< std::endl;
}
{
double theta = 0.79358805865013693;
show_fe_current_rounding_method();
volatile double output1 = cos(theta);
std::cout << std::setprecision(
std::numeric_limits<double>::digits10 + 1)
<< output1 << std::endl;
fesetround(FE_DOWNWARD);
show_fe_current_rounding_method();
volatile double output2 = cos(theta);
std::cout << std::setprecision(
std::numeric_limits<double>::digits10 + 1)
<< output2 << std::endl;
fesetround(FE_UPWARD);
show_fe_current_rounding_method();
volatile double output3 = cos(theta);
std::cout << std::setprecision(
std::numeric_limits<double>::digits10 + 1)
<< output3 << std::endl;
fesetround(FE_TOWARDZERO);
show_fe_current_rounding_method();
volatile double output4 = cos(theta);
std::cout << std::setprecision(
std::numeric_limits<double>::digits10 + 1)
<< output4 << std::endl;
}
}