BSD 4_3_Net_2 release

[unix-history] / usr / src / lib / libc / stdlib / random.3

diff --git a/usr/src/lib/libc/stdlib/random.3 b/usr/src/lib/libc/stdlib/random.3
index f7c6a37..872983c 100644 (file)
--- a/usr/src/lib/libc/stdlib/random.3
+++ b/usr/src/lib/libc/stdlib/random.3
@@ -1,43 +1,59 @@
-.\" Copyright (c) 1983 The Regents of the University of California.
+.\" Copyright (c) 1983, 1991 The Regents of the University of California.

 .\" All rights reserved.
 .\"
 .\" All rights reserved.
 .\"

-.\" Redistribution and use in source and binary forms are permitted
-.\" provided that the above copyright notice and this paragraph are
-.\" duplicated in all such forms and that any documentation,
-.\" advertising materials, and other materials related to such
-.\" distribution and use acknowledge that the software was developed
-.\" by the University of California, Berkeley.  The name of the
-.\" University may not be used to endorse or promote products derived
-.\" from this software without specific prior written permission.
-.\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
-.\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
-.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"    This product includes software developed by the University of
+.\"    California, Berkeley and its contributors.
+.\" 4. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.

 .\"
 .\"

-.\"    @(#)random.3    6.3 (Berkeley) %G%
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.

 .\"
 .\"

-.UC 7
-.TH RANDOM 3 ""
-.UC 5
-.SH NAME
-random, srandom, initstate, setstate \- better random number generator; routines for changing generators
-.SH SYNOPSIS
-.nf
-.B long  random()
-.PP
-.B srandom(seed)
-.B int  seed;
-.PP
-.B char  *initstate(seed, state, n)
-.B unsigned  seed;
-.B char  *state;
-.B int  n;
-.PP
-.B char  *setstate(state)
-.B char  *state;
-.fi
-.SH DESCRIPTION
-.PP
-.I Random
+.\"     @(#)random.3   6.5 (Berkeley) 4/19/91
+.\"
+.Dd April 19, 1991
+.Dt RANDOM 3
+.Os BSD 4.2
+.Sh NAME
+.Nm random ,
+.Nm srandom ,
+.Nm initstate ,
+.Nm setstate
+.Nd better random number generator; routines for changing generators
+.Sh SYNOPSIS
+.Fd #include <stdlib>
+.Ft long 
+.Fn random void
+.Ft void
+.Fn srandom "unsigned seed"
+.Ft char *
+.Fn initstate "unsigned seed" "char *state" "int n"
+.Ft char *
+.Fn setstate "char *state"
+.Sh DESCRIPTION
+The
+.Fn random
+function

 uses a non-linear additive feedback random number generator employing a
 default table of size 31 long integers to return successive pseudo-random
 numbers in the range from 0 to
 uses a non-linear additive feedback random number generator employing a
 default table of size 31 long integers to return successive pseudo-random
 numbers in the range from 0 to


@@ -46,95 +62,105 @@ numbers in the range from 0 to
 The period of this random number generator is very large, approximately
 .if t 16\(mu(2\u\s731\s10\d\(mi1).
 .if n 16*((2**31)\(mi1).
 The period of this random number generator is very large, approximately
 .if t 16\(mu(2\u\s731\s10\d\(mi1).
 .if n 16*((2**31)\(mi1).

-.PP
-.I Random/srandom
+.Pp
+The
+.Fn random Ns / Fn srandom

 have (almost) the same calling sequence and initialization properties as
 have (almost) the same calling sequence and initialization properties as

-.I rand/srand.
+.Xr rand 3 Ns / Xr srand 3 .

 The difference is that
 The difference is that

-.IR rand (3)
+.Xr rand

 produces a much less random sequence \(em in fact, the low dozen bits
 generated by rand go through a cyclic pattern.  All the bits generated by
 produces a much less random sequence \(em in fact, the low dozen bits
 generated by rand go through a cyclic pattern.  All the bits generated by

-.I random
-are usable.  For example, ``random()&01'' will produce a random binary
+.Fn random
+are usable.  For example,
+.Sq Li random()&01
+will produce a random binary

 value.
 value.

-.PP
+.Pp

 Unlike
 Unlike

-.IR srand ,
-.I srandom
+.Xr srand ,
+.Fn srandom

 does not return the old seed; the reason for this is that the amount of
 state information used is much more than a single word.  (Two other
 routines are provided to deal with restarting/changing random
 number generators).  Like
 does not return the old seed; the reason for this is that the amount of
 state information used is much more than a single word.  (Two other
 routines are provided to deal with restarting/changing random
 number generators).  Like

-.IR rand (3),
+.Xr rand 3 ,

 however,
 however,

-.I random
+.Fn random

 will by default produce a sequence of numbers that can be duplicated
 by calling
 will by default produce a sequence of numbers that can be duplicated
 by calling

-.I srandom
+.Fn srandom

 with 
 with 

-.I 1
+.Ql 1

 as the seed.
 as the seed.

-.PP
+.Pp

 The
 The

-.I initstate
+.Fn initstate

 routine allows a state array, passed in as an argument, to be initialized
 for future use.  The size of the state array (in bytes) is used by
 routine allows a state array, passed in as an argument, to be initialized
 for future use.  The size of the state array (in bytes) is used by

-.I initstate
-to decide how sophisticated a random number generator it should use -- the
+.Fn initstate
+to decide how sophisticated a random number generator it should use \(em the

 more state, the better the random numbers will be.
 (Current "optimal" values for the amount of state information are
 8, 32, 64, 128, and 256 bytes; other amounts will be rounded down to
 more state, the better the random numbers will be.
 (Current "optimal" values for the amount of state information are
 8, 32, 64, 128, and 256 bytes; other amounts will be rounded down to

-the nearest known amount.  Using less than 8 bytes will cause an error).
+the nearest known amount.  Using less than 8 bytes will cause an error.)

 The seed for the initialization (which specifies a starting point for
 the random number sequence, and provides for restarting at the same
 point) is also an argument.
 The seed for the initialization (which specifies a starting point for
 the random number sequence, and provides for restarting at the same
 point) is also an argument.

-.I Initstate
+The
+.Fn initstate
+function

 returns a pointer to the previous state information array.
 returns a pointer to the previous state information array.

-.PP
+.Pp

 Once a state has been initialized, the
 Once a state has been initialized, the

-.I setstate
+.Fn setstate

 routine provides for rapid switching between states.
 routine provides for rapid switching between states.

-.I Setstate
+The
+.Fn setstate
+function

 returns a pointer to the previous state array; its
 argument state array is used for further random number generation
 until the next call to
 returns a pointer to the previous state array; its
 argument state array is used for further random number generation
 until the next call to

-.I initstate
+.Fn initstate

 or
 or

-.I setstate.
-.PP
+.Fn setstate .
+.Pp

 Once a state array has been initialized, it may be restarted at a
 different point either by calling
 Once a state array has been initialized, it may be restarted at a
 different point either by calling

-.I initstate
+.Fn initstate

 (with the desired seed, the state array, and its size) or by calling
 both
 (with the desired seed, the state array, and its size) or by calling
 both

-.I setstate
+.Fn setstate

 (with the state array) and
 (with the state array) and

-.I srandom
+.Fn srandom

 (with the desired seed).
 The advantage of calling both
 (with the desired seed).
 The advantage of calling both

-.I setstate
+.Fn setstate

 and
 and

-.I srandom
+.Fn srandom

 is that the size of the state array does not have to be remembered after
 it is initialized.
 is that the size of the state array does not have to be remembered after
 it is initialized.

-.PP
+.Pp

 With 256 bytes of state information, the period of the random number
 generator is greater than
 .if t 2\u\s769\s10\d,
 .if n 2**69
 which should be sufficient for most purposes.
 With 256 bytes of state information, the period of the random number
 generator is greater than
 .if t 2\u\s769\s10\d,
 .if n 2**69
 which should be sufficient for most purposes.

-.SH AUTHOR
+.Sh AUTHOR

 Earl T. Cohen
 Earl T. Cohen

-.SH DIAGNOSTICS
-.PP
+.Sh DIAGNOSTICS

 If
 If

-.I initstate
+.Fn initstate

 is called with less than 8 bytes of state information, or if
 is called with less than 8 bytes of state information, or if

-.I setstate
+.Fn setstate

 detects that the state information has been garbled, error
 messages are printed on the standard error output.
 detects that the state information has been garbled, error
 messages are printed on the standard error output.

-.SH "SEE ALSO"
-rand(3)
-.SH BUGS
+.Sh SEE ALSO
+.Xr rand 3
+.Sh HISTORY
+These
+functions appeared in 
+.Bx 4.2 .
+.Sh BUGS

 About 2/3 the speed of
 About 2/3 the speed of

-.IR rand (3C).
+.Xr rand 3 .