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From Jian Lin:
A simple and convenient unit convert with constant lists. Get conversions for all units simultaneously, and use entire display height to show information. Features (not all units / constants will show in this free version): Constant lists including physical, chemical and nature constants. Convert simultaneously all units of the same type. Use the entire height of ipad display to show units. Pop-up number keyboard only shows up when needed. Both portrait and landscape modes are supported. Spectroscopy units are also included other than commonly used units, enable the conversion between wavelength, wavenumber, photon energy, and light frequency (available after purchase).