|Library for atmospheric/air speed computations, intended for aeronautical engineers and students. It can be used to compute atmospheric properties (temperature, pressure, density, and kinematic viscosity) and acceleration of gravity from altitude and, vice versa, to obtain the altitude corresponding to the value of one of these quantities. Using the altitude and an air speed related quantity, the library can compute (for both subsonic and supersonic regimes) True, Equivalent and Calibrated Air Speed, Mach number, Dynamic Pressure and Reynolds number per unit of length. Finally, the library can be used to compute "kink altitudes", i.e. altitudes corresponding to intersections on an aircraft airspeed diagram between constant Mach number lines and constant True/Equivalent/Calibrated Air Speed lines or constant Dynamic Pressure lines. Through the use of a reserved variable content, it implements a method for Non Standard Day Temperature correction. The library supports both SI units and Imperial units. Two versions of the library are provided (one for the 49G and one for the 49g+/50g) as well as a text documentation file to be loaded on a SD card and used in conjunction with the SDIAG library (see the Emacs package). Completely written in System RPL.