#include <cmath>
#include <iostream>
 
int main() 
{
    const double h = 6.62606957e-34; // Planck constant
    const double c = 299792458.0; // speed of light in vacuum
    const double k = 1.3806488e-23; // Boltzmann constant
    const double wl = 380;
    const double T = 100;
 
    double wavelength = wl * 1e-9;
 
    double exparg = h*c / (k*wavelength*T);
    std::cout << "Exparg:  " << exparg << std::endl;
    double exppart = std::exp(exparg) - 1.0;
    std::cout << "Exppart:  " << exppart << std::endl;
    return 0;
}

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