1.\" $NetBSD: factor.6,v 1.14 2017/11/11 23:48:44 rin Exp $ 2.\" 3.\" Copyright (c) 1989, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Landon Curt Noll. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" @(#)factor.6 8.1 (Berkeley) 5/31/93 34.\" 35.\" 36.\" By Landon Curt Noll, http://www.isthe.com/chongo/index.html /\oo/\ 37.\" 38.Dd Nov 12, 2017 39.Dt FACTOR 6 40.Os 41.Sh NAME 42.Nm factor 43.Nd factor a number 44.Sh SYNOPSIS 45.Nm 46.Op Fl h 47.Op Ar number ... 48.Sh DESCRIPTION 49The 50.Nm 51utility factors integers larger than 1. 52When a number is factored, it is printed, followed by a 53.Dq \&: , 54and the list of 55.Pq prime 56factors on a single line. 57Factors are listed in ascending order, and are preceded by a space. 58By default, if a factor divides a value more than once, it will be 59printed more than once. 60.Pp 61When 62.Nm 63is invoked with one or more 64.Ar number 65arguments, each argument will be factored. 66.Pp 67When 68.Nm 69is invoked with no 70.Ar number 71arguments, 72.Nm 73reads numbers, one per line, from standard input, until end of file or error. 74Leading white-space and empty lines are ignored. 75Numbers may be preceded by a single +. 76Integer less than 2 are rejected. 77Numbers are terminated by a non-digit character (such as a newline). 78After a number is read, it is factored. 79Input lines must not be longer than 80.Dv LINE_MAX \- 1 81(currently 2047) characters. 82.Pp 83By default, 84.Nm 85is compiled against the OpenSSL bignum implementation 86.Xr openssl_bn 3 , 87which lets it handle arbitrarily large values. 88.Pq Note however that very large values can take a very long time to factor. 89If 90.Nm 91is compiled without OpenSSL it is limited to the maximum value of 92.Vt unsigned long . 93.Pp 94The following option is available: 95.Bl -tag -width flag 96.It Fl h 97If the 98.Fl h 99flag is specified, factors will be printed in "human-readable" format. 100If a factor x divides a value n (>1) times, it will appear as x^n. 101.El 102.Sh DIAGNOSTICS 103Out of range or invalid input results in 104an appropriate error message to standard error. 105.Sh AUTHORS 106Originally by 107.An Landon Curt Noll . 108