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114 lines
4.0 KiB
114 lines
4.0 KiB
.\" |
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.\" $Id: random_range_seed.3,v 1.1 2000/07/27 16:59:03 alaffin Exp $ |
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.\" |
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.\" Copyright (c) 2000 Silicon Graphics, Inc. All Rights Reserved. |
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.\" |
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.\" This program is free software; you can redistribute it and/or modify it |
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.\" under the terms of version 2 of the GNU General Public License as |
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.\" published by the Free Software Foundation. |
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.\" |
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.\" This program is distributed in the hope that it would be useful, but |
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.\" WITHOUT ANY WARRANTY; without even the implied warranty of |
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.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
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.\" |
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.\" Further, this software is distributed without any warranty that it is |
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.\" free of the rightful claim of any third person regarding infringement |
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.\" or the like. Any license provided herein, whether implied or |
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.\" otherwise, applies only to this software file. Patent licenses, if |
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.\" any, provided herein do not apply to combinations of this program with |
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.\" other software, or any other product whatsoever. |
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.\" |
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.\" You should have received a copy of the GNU General Public License along |
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.\" with this program; if not, write the Free Software Foundation, Inc., |
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.\" 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
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.\" |
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.\" Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy, |
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.\" Mountain View, CA 94043, or: |
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.\" |
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.\" http://www.sgi.com |
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.\" |
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.\" For further information regarding this notice, see: |
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.\" |
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.\" http://oss.sgi.com/projects/GenInfo/NoticeExplan/ |
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.\" |
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.TH random_range 3 07/25/2000 "Linux Test Project" |
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.SH NAME |
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random_range \- a set of routines for dealing with integer ranges, and random numbers in a range |
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.SH SYNOPSIS |
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.nf |
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void random_range_seed(int seed) |
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long random_range(int min, int max, int mult, char **errp) |
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long random_rangel(long min, long max, long mult, char **errp) |
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long long random_rangell(long long min, long long max, |
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long long mult, char **errp) |
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long random_bit(long mask) |
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.fi |
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.SH DESCRIPTION |
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This is a set of routines for parsing numeric ranges, and choosing random |
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numbers from a range. |
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random_range() chooses a random number in the range min-max (inclusive) which |
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is a multiple of mult. min and max may be any integer, but mult must be |
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a positive integer greater than 0. errp is a char ** which is used to detect |
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error conditions. If errp is not NULL, *errp will be set to point to an |
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error message. If errp is NULL, error conditions cannot be detected by the |
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caller. If mult is 1 (the most common case), there are no possible error |
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conditions, and the return value is guaranteed to be valid. |
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random_range_seed() sets the random number generator seed to the specified |
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value. |
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random_bit() will return a randomly selected single bit bitmask from the bits |
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set in mask. The bit is randomly chosen using random_range(). |
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If mask is zero, zero is returned. |
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random_range() functions uses lrand48() internally. If the range is bigger |
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than will fit in a 32 bit long (2G), lrand48() with a |
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a internal recursive algorithm to produce a random number. |
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.SH EXAMPLES |
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\fC |
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.ta .25i +.25i +.25i +.25i |
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.nf |
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#include <stdio.h> |
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main(argc, argv) |
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int argc; |
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char **argv; |
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{ |
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int r; |
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char *errp; |
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extern void random_range_seed(); |
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extern long random_range(); |
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random_range_seed(getpid()); |
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r = random_range(atoi(argv[1]), atoi(argv[2]), atoi(argv[3]), &errp); |
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if (errp == NULL) { |
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fprintf(stderr, "random_range failed: %s\n", errp); |
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exit(1); |
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} else { |
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printf("%d\n", r); |
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} |
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exit(0); |
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} |
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\fP |
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.fi |
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.SH "SEE ALSO" |
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lrand48(3c) |
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.SH DIAGNOSTICS |
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If random_range() fails, errp will point to NULL, and the return value will be |
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undefined. If mult is 1, there are no possible error conditions, so the return |
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value is always valid in this case. |
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.SH BUGS |
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On CRAY systems, random_range(), random_rangel(), random_rangell() |
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all have the 64 bit limit since int, long and long long are always 64 bits. |
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On IRIX systems, random_range() can only produce a 32 number. |
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random_rangel() when compiled as a 32 bit object is still limited to 32 bit |
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number. random_rangell() can be used to return a value bigger than 32 bits |
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even when compiled as a 32 bit object. |
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