int undump(const char * file1, const char * file2) {
std::ifstream ifs(file1);
std::ofstream ofs(file2);
for (std::istream_iterator<double> it(ifs), eof; it != eof; ++it) {
ofs.write(reinterpret_cast<const char *>(& * it), sizeof(* it));
}
ifs.close();
ofs.close();
return 0;
}