1.\" $NetBSD: factor.6,v 1.12 2010/05/15 21:22:39 joerg 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 chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo 37.\" 38.\" chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\ 39.\" 40.Dd May 15, 2010 41.Dt FACTOR 6 42.Os 43.Sh NAME 44.Nm factor 45.Nd factor a number 46.Sh SYNOPSIS 47.Nm 48.Op Ar number ... 49.Sh DESCRIPTION 50The 51.Nm 52utility factors integers larger than 1. 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. 59If a factor divides a value more than once, it will be printed more than once. 60.Pp 61When 62.Nm 63is invoked with one or more arguments, each argument will be factored. 64.Pp 65When 66.Nm 67is invoked with no arguments, 68.Nm 69reads numbers, one per line, from standard input, until end of file or error. 70Leading white-space and empty lines are ignored. 71Numbers may be preceded by a single +. 72Integer less than 2 are rejected. 73Numbers are terminated by a non-digit character (such as a newline). 74After a number is read, it is factored. 75Input lines must not be longer than 76.Dv LINE_MAX \- 1 77(currently 2047) characters. 78.Pp 79By default, 80.Nm 81is compiled against the OpenSSL bignum implementation 82.Xr openssl_bn 3 , 83which lets it handle arbitrarily large values. 84.Pq Note however that very large values can take a very long time to factor. 85If 86.Nm 87is compiled without OpenSSL it is limited to the maximum value of 88.Vt unsigned long . 89.Sh DIAGNOSTICS 90Out of range or invalid input results in 91an appropriate error message 92being written to standard error. 93.\".Sh BUGS 94.\".Nm 95.\"cannot handle the 96.\".Dq 10 most wanted 97.\"factor list. 98