NAME

units − conversion program

SYNOPSIS

­units [ ­-v ] [ ­file ]

DESCRIPTION

­Units converts quantities expressed in various standard scales to their equivalents in other scales.  It works interactively in this fashion:

you have: inch
you want: cm
    ∗ 2.54
    / 0.393701

A quantity is specified as a multiplicative combination of units and floating point numbers.  Operators have the following precedence:

+ -add and subtract
∗ / × ÷multiply and divide
catenationmultiply
² ³ ^exponentiation
|divide
( ... )grouping

Most familiar units, abbreviations, and metric prefixes are recognized, together with a generous leavening of exotica and a few constants of nature including:

pi,πratio of circumference to diameter
cspeed of light
echarge on an electron
gacceleration of gravity
forcesame as g
moleAvogadro’s number
waterpressure head per unit height of water
auastronomical unit

The ­pound is a unit of mass.  Compound names are run together, e.g.  lightyear.  British units that differ from their US counterparts are prefixed thus: brgallon.  Currency is denoted belgiumfranc, britainpound, etc. 

The complete list of units can be found in /lib/units.  A ­file argument to ­units specifies a file to be used instead of /lib/units.  The ­-v flag causes ­units to print its entire database. 

EXAMPLE

you have: 15 pounds force/in²
you want: atm
    ∗ 1.02069
    / .97973

FILES

­/lib/units

SOURCE

­/sys/src/cmd/units.y

BUGS

Since ­units does only multiplicative scale changes, it can convert Kelvin to Rankine but not Centigrade to Fahrenheit. 
Currency conversions are only as accurate as the last time someone updated /lib/units. 

Plan 9  —  March 27, 2001