sinhatanh-exceptions

#include <stdio.h>
#include <math.h>
#include <float.h>
#include <fenv.h>
#include <typeinfo>
#include <iomanip>
#include <iostream>
#include <limits>
#include <errno.h>

#define PREC 10

#define qNAN (std::numeric_limits<double>::quiet_NaN())
#define sNAN (std::numeric_limits<double>::signaling_NaN())
#define INF (1./0.)

#define debug(msg, x) std::cout << std::scientific << std::setprecision(PREC) << msg << " = " << x << std::endl;

template<class R>
R sinhatanh(R x)
{
    if (typeid(R) == typeid(float))
        return sinhf(atanhf(x));
    else if (typeid(R) == typeid(double))
        return sinh(atanh(x));
    else if (typeid(R) == typeid(long double))
        return sinhl(atanhl(x));

    __builtin_unreachable();
}

template<class R>
R sinhatanh2_dijkstra(R x)
{
    if (typeid(R) == typeid(float))
        return x/sqrtf((1-x)*(1+x));
    else if (typeid(R) == typeid(double))
        return x/sqrt((1-x)*(1+x));
    else if (typeid(R) == typeid(long double))
        return x/sqrtl((1-x)*(1+x));
    __builtin_unreachable();
}

template<class R>
R coshatanh(R x)
{
    if (typeid(R) == typeid(float))
        return coshf(atanhf(x));
    else if (typeid(R) == typeid(double))
        return cosh(atanh(x));
    else if (typeid(R) == typeid(long double))
        return coshl(atanhl(x));

    __builtin_unreachable();
}

template<class R>
R coshatanh2_dijkstra(R x)
{
    R ret;
    if (typeid(R) == typeid(float))
        ret =  1/sqrtf((1-x)*(1+x));
    else if (typeid(R) == typeid(double))
        ret =  1/sqrt((1-x)*(1+x));
    else if (typeid(R) == typeid(long double))
        ret = 1/sqrtl((1-x)*(1+x));
    return ret;
}

#define ARR_LEN(x) (sizeof(x)/sizeof(x[0]))

int main()
{
    static const double values[] = {-qNAN, -sNAN, -INF -1., -0., +0., 1., INF, sNAN, qNAN};
    int i;

    for (i = 0; i < ARR_LEN(values); ++i)
    {
        double before = sinhatanh(values[i]);
        int err_before = errno;
        double after  = sinhatanh2_dijkstra(values[i]);
        int err_after = errno;

        debug("before: ", before);
        debug("after : ", after)

        if (err_before != err_after)
            std::cout << "Errno changed!" << std::endl;

    }

    return 0;
}