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Units is a cross-platform computer program for conversion of units of quantities. It has a database of measurements, including esoteric and historical measurements. This for instance allows conversion of velocities specified in furlongs per fortnight, and pressures specified in tons per acre. The plain text database units.dat is a good reference in itself, as it is extensively commented and cites numerous sources.
UDUNITS is a similar utility program, except that it has an additional programming library interface and date conversion abilities. UDUNITS is considered the de facto program and library for variable unit conversion for netCDF files.
Units will output the result of the conversion in two lines. Usually the first line (multiplication) is the desired result. The second line is the same conversion expressed as a division.
If you attempt to convert types of measurements that are incompatible units will print a conformability error message and display a reduced form of each measurement.
2083 units, 71 prefixes, 32 nonlinear units You have: 10 furlongs You want: miles * 1.2500025 / 0.7999984 You have: 1 gallon + 3 pints You want: quarts * 5.5 / 0.18181818 You have: sqrt(miles^2) You want: Definition: 1609.344 m You have:
On the command line (non-interactive)
% units 'ten furlongs per fortnight' 'kilometers per hour' * 0.0059871548 / 167.02424
% units cup ounces conformability error 0.00023658824 m^3 0.028349523 kg
- ↑ As specified from several NetCDF conventions, e.g.: