You have: meters
You want: feet
* 3.2808399
/ 0.3048
You have: cm^3
You want: gallons
* 0.00026417205
/ 3785.4118
Powers of units can be specified using the '^' character as shown in
the example, or by simple concatenation: 'cm3' is equivalent to 'cm^3'.
Multiplication of units can be specified by using spaces, a dash or
an asterisk. Division of units is indicated by the slash ('/').
Note that multiplication has a higher precedence than division, so
If the user enters incompatible unit types, the units program will
print a message indicating that the units are not conformable and
it will display the reduced form for each unit:
You have: ergs/hour
You want: fathoms kg^2 / day
conformability error
2.7777778e-11 kg m^2 / sec^3
2.1166667e-05 kg^2 m / sec
The conversion information is read from a units data file. The default
file includes definitions for most familiar units, abbreviations and
metric prefixes. Some constants of nature included are:
piratio of circumference to diameter
cspeed of light
echarge on an electron
gacceleration of gravity
forcesame as g
moleAvogadro's number
waterpressure per unit height of water
mercurypressure per unit height of mercury
auastronomical unit
'Pound' is a unit of mass. Compound names are run together
so 'poundforce' is a unit of force. British units that differ from their
US counterparts are prefixed with 'br', and currency is prefixed with
its country name: 'belgiumfranc', 'britainpound'. When searching for
a unit, if the specified string does not appear exactly as a unit
name, then the units program will try to remove a trailing 's' or
a trailing 'es' and check again for a match.
All of these definitions can be read in the standard units file, or you can supply your own file. A unit is specified on a single line by giving its name and an equivalence. One should be careful to define new units in terms of old ones so that a reduction leads to the primitive units which are marked with '!' characters. The units program will not detect infinite loops that could be caused by careless unit definitions.
Prefixes are defined in the same was as standard units, but with a trailing dash at the end of the prefix name.
The effect of including a '/' in a prefix is surprising.
Exponents entered by the user can be only one digit.
The user must use | to indicate division of numbers and / to indicate division of symbols. This distinction should not be necessary.
The program contains various arbitrary limits on the length of the units converted and on the length of the data file.