1.\" $NetBSD: factor.6,v 1.18 2020/10/12 13:53:43 christos 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 October 12, 2020 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 hx 47.Op Ar number ... 48.Sh DESCRIPTION 49The 50.Nm 51utility factors integers larger than 52.Dv 0 . 53When a number is factored, it is printed, followed by a 54.Dq \&: , 55and the list of 56.Pq prime 57factors on a single line. 58Factors are listed in ascending order, and are preceded by a space. 59By default, if a factor divides a value more than once, it will be 60printed more than once. 61.Pp 62When 63.Nm 64is invoked with one or more 65.Ar number 66arguments, each argument will be factored. 67.Pp 68When 69.Nm 70is invoked with no 71.Ar number 72arguments, 73.Nm 74reads numbers, one per line, from standard input, until end of file or error. 75Leading white-space and empty lines are ignored. 76Numbers may be preceded by a single +. 77Numbers that start with 78.Dv 0x 79are interpreted as hexadecimal. 80A 81.Dv 0 82input exits the program. 83Negative numbers are not allowed. 84Numbers are terminated by a non-digit character (such as a newline). 85After a number is read, it is factored. 86Input lines must not be longer than 87.Dv LINE_MAX \- 1 88(currently 2047) characters. 89.Pp 90By default, 91.Nm 92is compiled against the OpenSSL bignum implementation 93.Xr openssl_bn 3 , 94which lets it handle arbitrarily large values. 95.Pq Note however that very large values can take a very long time to factor. 96If 97.Nm 98is compiled without OpenSSL it is limited to the maximum value of 99.Vt unsigned long . 100.Pp 101The following option is available: 102.Bl -tag -width flag 103.It Fl h 104If the 105.Fl h 106flag is specified, factors will be printed in "human-readable" format. 107If a factor x divides a value n (>1) times, it will appear as x^n. 108.It Fl x 109If the 110.Fl x 111flag is specified, factors will be printed in hexadecimal format. 112.El 113.Sh DIAGNOSTICS 114Out of range or invalid input results in 115an appropriate error message to standard error. 116.Sh AUTHORS 117Originally by 118.An Landon Curt Noll . 119