Function fast_exp

library/cpp/fast_exp/fast_exp.cpp:33–49

}

double fast_exp(double x) {
    double arg = x;
    double res = 1;

    const auto& expTable = HugeSingletonWithPriority<TTable, 0>()->ExpTable;

    for (int iter = 0; iter < 4; ++iter) {
        TDoubleInt dd;
        dd.FVal = arg;
        double chk = expTable[dd.IVal >> 48];
        dd.IVal &= 0xffff000000000000ll;
        res *= chk;
        arg -= dd.FVal;
    }

    return res * (1 + arg);
}

void FastExpInplace(double* x, size_t count) {
#if defined(_x86_64_) || defined(_i386_)