factor.6

早期freebsd实现

.\" Copyright (c) 1989, 1993
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.\" Landon Curt Noll.
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.\"	@(#)factor.6	8.1 (Berkeley) 5/31/93
.\"
.\"
.\" By: Landon Curt Noll   [e-mail],   ...!{sun,tolsoft}!hoptoad!chongo
.\"
.\"   chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
.\"
.TH FACTOR 6 "May 31, 1993"
.UC 7
.SH NAME
factor, primes \- factor a number, generate primes
.SH SYNOPSIS
.B factor
[ number ] ...
.PP
.B primes
[ start [ stop ]]
.SH DESCRIPTION
The
.I factor
utility will factor integers between -2147483648 and 2147483647 inclusive.
When a number is factored, it is printed, followed by a ``:'',
and the list of factors on a single line.
Factors are listed in ascending order, and are preceded by a space.
If a factor divides a value more than once, it will be printed
more than once.
.PP
When
.I factor
is invoked with one or more arguments,
each argument will be factored.
.PP
When
.I factor
is invoked with no arguments,
.I factor
reads numbers, one per line, from standard input, until end of file or error.
Leading white-space and empty lines are ignored.
Numbers may be preceded by a single - or +.
Numbers are terminated by a non-digit character (such as a newline).
After a number is read, it is factored.
Input lines must not be longer than 255 characters.
.PP
The
.I primes
utility prints primes in ascending order, one per line, starting at or above
.B start
and continuing until, but not including
.B stop.
The
.B start 
value must be at least 0 and not greater than
.B stop.\&
The
.B stop
value must not be greater than 4294967295.
The default value of
.B stop
is 4294967295.
.PP
When the
.I primes
utility is invoked with no arguments,
.B start
is read from standard input.
.B Stop
is taken to be 4294967295.
The
.B start
value may be preceded by a single +.
The
.B start
value is terminated by a non-digit character (such as a newline).
The input line must not be longer than 255 characters.
.SH DIAGNOSTICS
Out of range or invalid input results in `ouch' being 
written to standard error.
.SH BUGS
.I Factor
cannot handle the ``10 most wanted'' factor list,
.I primes
won't get you a world record.