xref: /dragonfly/games/factor/factor.6 (revision 333227be)
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4.\" This code is derived from software contributed to Berkeley by
5.\" Landon Curt Noll.
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35.\"	@(#)factor.6	8.1 (Berkeley) 5/31/93
36.\"
37.\" $FreeBSD: src/games/factor/factor.6,v 1.5.2.3 2003/01/26 02:54:56 keramida Exp $
38.\" $DragonFly: src/games/factor/factor.6,v 1.2 2003/06/17 04:25:23 dillon Exp $
39.\"
40.\" By: Landon Curt Noll   chongo@toad.com,   ...!{sun,tolsoft}!hoptoad!chongo
41.\"
42.\"   chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
43.\"
44.Dd October 10, 2002
45.Dt FACTOR 6
46.Os
47.Sh NAME
48.Nm factor , primes
49.Nd factor a number, generate primes
50.Sh SYNOPSIS
51.Nm
52.Op Fl h
53.Op Ar number ...
54.Nm primes
55.Op Fl h
56.Op Ar start Op Ar stop
57.Sh DESCRIPTION
58The
59.Nm
60utility will factor positive integers.
61When a number is factored, it is printed, followed by a
62.Ql \&: ,
63and the list of factors on a single line.
64Factors are listed in ascending order, and are preceded by a space.
65If a factor divides a value more than once, it will be printed more than once.
66.Pp
67When
68.Nm
69is invoked with one or more arguments, each argument will be factored.
70.Pp
71When
72.Nm
73is invoked with no arguments,
74.Nm
75reads numbers, one per line, from standard input, until end of file or error.
76Leading white-space and empty lines are ignored.
77Numbers may be preceded by a single
78.Ql + .
79Numbers are terminated by a non-digit character (such as a newline).
80After a number is read, it is factored.
81.Pp
82The
83.Nm primes
84utility prints primes in ascending order, one per line, starting at or above
85.Ar start
86and continuing until, but not including
87.Ar stop .
88The
89.Ar start
90value must be at least 0 and not greater than
91.Ar stop .
92The
93.Ar stop
94value must not be greater than the maximum.
95The default and maximum value of
96.Ar stop
97is 4294967295 on 32-bit architectures
98and 18446744073709551615 on 64-bit ones.
99.Pp
100When the
101.Nm primes
102utility is invoked with no arguments,
103.Ar start
104is read from standard input and
105.Ar stop
106is taken to be the maximum.
107The
108.Ar start
109value may be preceded by a single
110.Ql + .
111The
112.Ar start
113value is terminated by a non-digit character (such as a newline).
114.Sh DIAGNOSTICS
115.Bl -diag
116.It "negative numbers aren't permitted"
117.It "illegal numeric format"
118.It "start value must be less than stop value"
119.It "Result too large"
120.El
121.Sh BUGS
122.Nm
123cannot handle the
124.Dq "10 most wanted"
125factor list,
126.Nm primes
127will not get you a world record.
128