.\" Copyright (c) 1989, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Landon Curt Noll.
.\"
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.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\"	@(#)factor.6	8.1 (Berkeley) 5/31/93
.\"
.\" By: Landon Curt Noll   chongo@toad.com,   ...!{sun,tolsoft}!hoptoad!chongo
.\"
.\"   chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
.\"
.Dd January 12, 2020
.Dt FACTOR 6
.Os
.Sh NAME
.Nm factor , primes
.Nd factor a number, generate primes
.Sh SYNOPSIS
.Nm
.Op Fl h
.Op Ar number ...
.Nm primes
.Op Fl h
.Op Ar start Op Ar stop
.Sh DESCRIPTION
The
.Nm
utility will factor positive integers.
When a number is factored, it is printed, followed by a
.Ql \&: ,
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
.Nm
is invoked with one or more arguments, each argument will be factored.
.Pp
When
.Nm
is invoked with no arguments,
.Nm
reads numbers, one per line, from standard input until end of file or 0
is entered or an error occurs.
Leading white-space and empty lines are ignored.
.Pp
Numbers may be preceded by a single
.Ql + .
Numbers can be either decimal or hexadecimal strings where the longest
leading substring is used.
Numbers are terminated by a non-digit character (such as a newline).
If the string contains only decimal digits, it is treated as a
decimal representation for a number.
A hexadecimal string can contain an optional
.Em 0x
or
.Em 0X
prefix.
After a number is read, it is factored.
.Pp
The
.Nm primes
utility prints primes in ascending order, one per line, starting at or above
.Ar start
and continuing until, but not including
.Ar stop .
The
.Ar start
value must be at least 0 and not greater than
.Ar stop .
The
.Ar stop
value must not be greater than the maximum.
The default and maximum value of
.Ar stop
is 18446744073709551615.
.Pp
When the
.Nm primes
utility is invoked with no arguments,
.Ar start
is read from standard input and
.Ar stop
is taken to be the maximum.
The
.Ar start
value may be preceded by a single
.Ql + .
The
.Ar start
value is terminated by a non-digit character (such as a newline).
.Sh DIAGNOSTICS
.Bl -diag
.It "negative numbers aren't permitted"
.It "illegal numeric format"
.It "start value must be less than stop value"
.It "Result too large"
.El
.Sh BUGS
.Nm
cannot handle the
.Dq "10 most wanted"
factor list,
.Nm primes
will not get you a world record.