Note that if the value part of a units expression is exactly ‘1’, it will be removed by the Calculator’s automatic algebra routines: The formula ‘1 mm’ is “simplified” to ‘mm’. This is only a display anomaly, however; ‘mm’ will work just fine as a representation of one millimeter. Finally, trigonometric functions of quantities with units of angle are evaluated, regardless of the current angular mode. Continuing the above example, entering the units expression ‘100 km/hr’ and typing u c (without specifying new units) produces ‘27.7777777778 m/s’. The u c command treats temperature units (like ‘degC’ and ‘K’) as relative temperatures. The value on the stack must be a simple units expression with units of temperature only. For example, u c converts ‘10 degC’ to ‘18 degF’: A change of 10 degrees Celsius corresponds to a change of 18 degrees Fahrenheit. To convert absolute temperatures, you can use the u t (calc-convert-temperature) command.
For example, given the units expression ‘55 mph’, typing u c m/s produces ‘24.5872 m/s’. If you have previously converted a units expression with the same type of units (in this case, distance over time), you will be offered the previous choice of new units as a default. For example, u c si converts the expression into International System of Units (SI) base units. See Simplification Modes, for a way to have this done automatically at all times. Each of these classifications constitutes a separate section of the codes manual and each section contains a brief narrative statement regarding the nature and purpose of the data along with the actual codes and titles. While many of Calc’s conversion factors are exact, some are necessarily approximate. If Calc is in fraction mode (see Fraction Mode), then unit conversions will try to give exact, rational conversions, but it isn’t always possible. The u r (calc-remove-units) command removes units from the formula at the top of the stack.
The u a (calc-autorange-units) command turns on and off a mode in which unit prefixes like k (“kilo”) are automatically applied to keep the numeric part of a units expression in a reasonable range. This command would convert ‘10 degC’ to ‘50 degF’, the equivalent temperature on the Fahrenheit scale. The u c (calc-convert-units) command converts a units expression to new, compatible units. For example, to change ‘mi/hr’ to ‘km/hr’, you could type u c km , but u n km would signal an error. You can also define your own unit names; see User-Defined Units.