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Recommend use or random_r(3) for multithreaded appliucations that need 

independent, reproducible sequences of random numbers.
Move references to "The Art of Computer Programming" and "Numerical Recipes",
formerly in rand(3), to this page.
Add drand48(93) to SEE ALSO list.
This commit is contained in:
Michael Kerrisk 2008-03-03 16:51:35 +00:00
parent a5ed744769
commit 5b475602ef
1 changed files with 23 additions and 2 deletions
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man3/random.3
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@ -28,7 +28,7 @@
.\" Modified Sat Jul 24 18:13:39 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified Sun Aug 20 21:47:07 2000, aeb
.\"
.TH RANDOM 3 2007-07-26 "GNU" "Linux Programmer's Manual"
.TH RANDOM 3 2008-03-07 "GNU" "Linux Programmer's Manual"
.SH NAME
random, srandom, initstate, setstate \- random number generator
.SH SYNOPSIS
@ -54,7 +54,7 @@ Feature Test Macro Requirements for glibc (see
.BR srandom (),
.BR initstate (),
.BR setstate ():
_SVID_SOURCE || |_BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500
_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 500
.ad b
.SH DESCRIPTION
The
@ -137,6 +137,27 @@ Current "optimal" values for the size of the state array \fIn\fP are
the nearest known amount.
Using less than 8 bytes will cause an
error.
.PP
This function should not be used in cases where multiple threads use
.BR random ()
and the behavior should be reproducible.
Use
.BR random_r (3)
for that purpose.
.PP
Random-number generation is a complex topic.
.I Numerical Recipes in C: The Art of Scientific Computing
(William H. Press, Brian P. Flannery, Saul A. Teukolsky, William
T. Vetterling; New York: Cambridge University Press, 2007, 3rd ed.)
provides an excellent discussion of practical random-number generation
issues in Chapter 7 (Random Numbers).
.PP
For a more theoretical discussion which also covers many practical issues
in depth, see Chapter 3 (Random Numbers) in Donald E. Knuth's
.IR "The Art of Computer Programming" ,
volume 2 (Seminumerical Algorithms), 2nd ed.; Reading, Massachusetts:
Addison-Wesley Publishing Company, 1981.
.SH "SEE ALSO"
.BR drand48 (3),
.BR rand (3),
.BR srand (3)