Hello All, Thare is a problem in boost::format to treat infinity floating point values. Compare output of the two following lines of code: cout << numeric_limits<double>::infinity(); cout << boost::format("%f\n") % numeric_limits<double>::infinity(); The first one on my machine outputs 1.#INF which denotes infinity. The code with boost::format outputs 1/5000 zeroes/.#INF000 It's not what I can expect in any way. It's strange, but quiet NaN is outputed well. -- Vyacheslav E. Andrejev System Architect, Excelsior, LLC