units.1

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)units.1	8.1	9/11/90
.if n .ds / /
.if t .ds / \z/\h'\w'*'u'
.TH units 1 "" "" Unsupported
.SH Name
units \- conversion program
.SH Syntax
.B units
.SH Description
The
.PN units
command
converts quantities expressed
in various standard scales to
their equivalents in other scales.
It works interactively in this fashion:
.PP
.I "	You have:"
inch
.br
.I "	You want:"
cm
.br
.I "		* 2.54000e+00
.br
.I "		\*/ 3.93701e\-01
.PP
A quantity is specified as a multiplicative combination of
units optionally preceded by a numeric multiplier.
Powers are indicated by suffixed positive integers,
division by the usual sign:
.PP
.I "	You have:"
15 pounds force/in2
.br
.I "	You want:"
atm
.br
.I "		* 1.02069e+00"
.br
.I "		\*/ 9.79730e\-01"
.PP
The
.PN units 
command only does multiplicative scale changes.
Thus it can convert Kelvin to Rankine, but not Centigrade to
Fahrenheit.
Most familiar units,
abbreviations, and metric prefixes are recognized,
together with a generous leavening of exotica
and a few constants of nature including:
.PP
.nf
	pi	ratio of circumference to diameter
	c	speed of light
	e	charge on an electron
	g	acceleration of gravity 
	force	same as g
	mole	Avogadro's number
	water	pressure head per unit height of water
	au	astronomical unit
.PP
.fi
`Pound' is a unit of
mass.
Compound names are run together, for example, `lightyear'.
British units that differ from their US counterparts
are prefixed thus: `brgallon'.
Currency is denoted `belgiumfranc', `britainpound', ...
.PP
If 
.PN units
is used with no arguments, it will use 
.PN /usr/lib/units
to define the units and the conversions that it knows about.
When
.I file
is supplied, it will be used to define the units and conversions 
that 
.PN units
will recognize.
.SH Files
.PN /usr/lib/units