+++ /dev/null
-.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
-.\"
-.\" %%%LICENSE_START(VERBATIM)
-.\" Permission is granted to make and distribute verbatim copies of this
-.\" manual provided the copyright notice and this permission notice are
-.\" preserved on all copies.
-.\"
-.\" Permission is granted to copy and distribute modified versions of this
-.\" manual under the conditions for verbatim copying, provided that the
-.\" entire resulting derived work is distributed under the terms of a
-.\" permission notice identical to this one.
-.\"
-.\" Since the Linux kernel and libraries are constantly changing, this
-.\" manual page may be incorrect or out-of-date. The author(s) assume no
-.\" responsibility for errors or omissions, or for damages resulting from
-.\" the use of the information contained herein. The author(s) may not
-.\" have taken the same level of care in the production of this manual,
-.\" which is licensed free of charge, as they might when working
-.\" professionally.
-.\"
-.\" Formatted or processed versions of this manual, if unaccompanied by
-.\" the source, must acknowledge the copyright and authors of this work.
-.\" %%%LICENSE_END
-.\"
-.\" References consulted:
-.\" Linux libc source code
-.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
-.\" 386BSD man pages
-.\" Modified Sat Jul 24 19:46:03 1993 by Rik Faith (faith@cs.unc.edu)
-.TH DRAND48 3 2014-09-21 "" "Linux Programmer's Manual"
-.SH NAME
-drand48, erand48, lrand48, nrand48, mrand48, jrand48, srand48, seed48,
-lcong48 \- generate uniformly distributed pseudo-random numbers
-.SH SYNOPSIS
-.nf
-.B #include <stdlib.h>
-.sp
-.B double drand48(void);
-.sp
-.BI "double erand48(unsigned short " xsubi [3]);
-.sp
-.B long int lrand48(void);
-.sp
-.BI "long int nrand48(unsigned short " xsubi [3]);
-.sp
-.B long int mrand48(void);
-.sp
-.BI "long int jrand48(unsigned short " xsubi [3]);
-.sp
-.BI "void srand48(long int " seedval );
-.sp
-.BI "unsigned short *seed48(unsigned short " seed16v [3]);
-.sp
-.BI "void lcong48(unsigned short " param [7]);
-.fi
-.sp
-.in -4n
-Feature Test Macro Requirements for glibc (see
-.BR feature_test_macros (7)):
-.in
-.sp
-.ad l
-All functions shown above:
-.\" .BR drand48 (),
-.\" .BR erand48 (),
-.\" .BR lrand48 (),
-.\" .BR nrand48 (),
-.\" .BR mrand48 (),
-.\" .BR jrand48 (),
-.\" .BR srand48 (),
-.\" .BR seed48 (),
-.\" .BR lcong48 ():
-_SVID_SOURCE || _XOPEN_SOURCE
-.ad b
-.SH DESCRIPTION
-These functions generate pseudo-random numbers using the linear congruential
-algorithm and 48-bit integer arithmetic.
-.PP
-The
-.BR drand48 ()
-and
-.BR erand48 ()
-functions return nonnegative
-double-precision floating-point values uniformly distributed between
-[0.0, 1.0).
-.PP
-The
-.BR lrand48 ()
-and
-.BR nrand48 ()
-functions return nonnegative
-long integers uniformly distributed between 0 and 2^31.
-.PP
-The
-.BR mrand48 ()
-and
-.BR jrand48 ()
-functions return signed long
-integers uniformly distributed between \-2^31 and 2^31.
-.PP
-The
-.BR srand48 (),
-.BR seed48 ()
-and
-.BR lcong48 ()
-functions are
-initialization functions, one of which should be called before using
-.BR drand48 (),
-.BR lrand48 ()
-or
-.BR mrand48 ().
-The functions
-.BR erand48 (),
-.BR nrand48 ()
-and
-.BR jrand48 ()
-do not require
-an initialization function to be called first.
-.PP
-All the functions work by generating a sequence of 48-bit integers,
-.IR Xi ,
-according to the linear congruential formula:
-.sp
-.nf
-.RS
-.B Xn+1 = (aXn + c) mod m, where n >= 0
-.RE
-.fi
-.sp
-The parameter
-.I m
-= 2^48, hence 48-bit integer arithmetic is performed.
-Unless
-.BR lcong48 ()
-is called,
-.IR a
-and
-.I c
-are given by:
-.sp
-.nf
-.RS
-.B a = 0x5DEECE66D
-.B c = 0xB
-.RE
-.fi
-.sp
-The value returned by any of the functions
-.BR drand48 (),
-.BR erand48 (),
-.BR lrand48 (),
-.BR nrand48 (),
-.BR mrand48 ()
-or
-.BR jrand48 ()
-is
-computed by first generating the next 48-bit
-.I Xi
-in the sequence.
-Then the appropriate number of bits, according to the type of data item to
-be returned, is copied from the high-order bits of
-.I Xi
-and transformed
-into the returned value.
-.PP
-The functions
-.BR drand48 (),
-.BR lrand48 ()
-and
-.BR mrand48 ()
-store
-the last 48-bit
-.I Xi
-generated in an internal buffer.
-The functions
-.BR erand48 (),
-.BR nrand48 ()
-and
-.BR jrand48 ()
-require the calling
-program to provide storage for the successive
-.I Xi
-values in the array
-argument
-.IR xsubi .
-The functions are initialized by placing the initial
-value of
-.I Xi
-into the array before calling the function for the first
-time.
-.PP
-The initializer function
-.BR srand48 ()
-sets the high order 32-bits of
-.I Xi
-to the argument
-.IR seedval .
-The low order 16-bits are set
-to the arbitrary value 0x330E.
-.PP
-The initializer function
-.BR seed48 ()
-sets the value of
-.I Xi
-to
-the 48-bit value specified in the array argument
-.IR seed16v .
-The
-previous value of
-.I Xi
-is copied into an internal buffer and a
-pointer to this buffer is returned by
-.BR seed48 ().
-.PP
-The initialization function
-.BR lcong48 ()
-allows the user to specify
-initial values for
-.IR Xi ,
-.I a
-and
-.IR c .
-Array argument
-elements
-.I param[0-2]
-specify
-.IR Xi ,
-.I param[3-5]
-specify
-.IR a ,
-and
-.I param[6]
-specifies
-.IR c .
-After
-.BR lcong48 ()
-has been called, a subsequent call to either
-.BR srand48 ()
-or
-.BR seed48 ()
-will restore the standard values of
-.I a
-and
-.IR c .
-.SH ATTRIBUTES
-.SS Multithreading (see pthreads(7))
-The
-.BR drand48 (),
-.BR erand48 (),
-.BR lrand48 (),
-.BR nrand48 (),
-.BR mrand48 (),
-.BR jrand48 (),
-.BR srand48 (),
-.BR seed48 (),
-and
-.BR lcong48 ()
-functions record global state information for the random number generator,
-so they are not thread-safe.
-.SH CONFORMING TO
-SVr4, POSIX.1-2001.
-.SH SEE ALSO
-.BR rand (3),
-.BR random (3)
-.SH COLOPHON
-This page is part of release 3.79 of the Linux
-.I man-pages
-project.
-A description of the project,
-information about reporting bugs,
-and the latest version of this page,
-can be found at
-\%http://www.kernel.org/doc/man\-pages/.
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