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diff --git a/man/man3/rand.html b/man/man3/rand.html new file mode 100644 index 00000000..0601c6bf --- /dev/null +++ b/man/man3/rand.html @@ -0,0 +1,190 @@ +<head> +<title>rand(3) - Plan 9 from User Space</title> +<meta content="text/html; charset=utf-8" http-equiv=Content-Type> +</head> +<body bgcolor=#ffffff> +<table border=0 cellpadding=0 cellspacing=0 width=100%> +<tr height=10><td> +<tr><td width=20><td> +<tr><td width=20><td><b>RAND(3)</b><td align=right><b>RAND(3)</b> +<tr><td width=20><td colspan=2> + <br> +<p><font size=+1><b>NAME </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + rand, lrand, frand, nrand, lnrand, srand, truerand, ntruerand, + fastrand, nfastrand – random number generator<br> + +</table> +<p><font size=+1><b>SYNOPSIS </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <tt><font size=+1>#include <u.h><br> + #include <libc.h> + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>int rand(void) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>long lrand(void) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>double frand(void) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>int nrand(int val) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>long lnrand(long val) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>void srand(long seed) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>ulong truerand(void) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>ulong ntruerand(ulong val)<br> + #include <mp.h><br> + #include <libsec.h> + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>void genrandom(uchar *buf, int nbytes) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>void prng(uchar *buf, int nbytes) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>ulong fastrand(void) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>ulong nfastrand(ulong val)<br> + </font></tt> +</table> +<p><font size=+1><b>DESCRIPTION </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <i>Rand</i> returns a uniform pseudo-random number <i>x</i>, 0≤<i>x</i><215. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + <i>Lrand</i> returns a uniform <tt><font size=+1>long</font></tt> <i>x</i>, 0≤<i>x</i><231. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + <i>Frand</i> returns a uniform <tt><font size=+1>double</font></tt> <i>x</i>, 0.0≤<i>x</i><1.0, This function calls + <i>lrand</i> twice to generate a number with as many as 62 significant + bits of mantissa. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + <i>Nrand</i> returns a uniform integer <i>x</i>, 0≤<i>x</i><<i>val. Lnrand</i> is the same, + but returns a <tt><font size=+1>long</font></tt>. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + The algorithm is additive feedback with:<br> + + <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + x[n] = (x[n-273] + x[n-607]) mod 231 + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + + </table> + giving a period of 230 × (2607 – 1). + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + The generators are initialized by calling <i>srand</i> with whatever + you like as argument. To get a different starting value each time,<br> + + <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <tt><font size=+1>srand(time(0)) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + + </table> + will work as long as it is not called more often than once per + second. Calling<br> + + <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <tt><font size=+1>srand(1) + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + + </table> + will initialize the generators to their starting state. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + <i>Truerand</i> returns a random unsigned long read from <tt><font size=+1>/dev/random</font></tt>. + Due to the nature of <tt><font size=+1>/dev/random</font></tt>, truerand can only return a few + hundred bits a second. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + <i>Ntruerand</i> returns a uniform random integer <i>x</i>, 0≤<i>x</i><<i>val</i>≤<i>232-1. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </i> + <i>Genrandom</i> fills a buffer with bytes from the X9.17 pseudo-random + number generator. The X9.17 generator is seeded by 24 truly random + bytes read from <tt><font size=+1>/dev/random</font></tt>. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + <i>Prng</i> uses the native <a href="../man3/rand.html"><i>rand</i>(3)</a> pseudo-random number generator to + fill the buffer. Used with <i>srand</i>, this function can produce a + reproducible stream of pseudo random numbers useful in testing. + + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + Both <i>genrandom</i> and <i>prng</i> may be passed to <i>mprand</i> (see <a href="../man3/mp.html"><i>mp</i>(3)</a>). + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + <i>Fastrand</i> uses <i>genrandom</i> to return a uniform <tt><font size=+1>unsigned long</font></tt> <i>x</i>, 0≤<i>x</i><<i>232-1. + + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </i> + <i>Nfastrand</i> uses <i>genrandom</i> to return a uniform <tt><font size=+1>unsigned long</font></tt> <i>x</i>, + 0≤<i>x</i><<i>val</i>≤<i>232-1.<br> + </i> +</table> +<p><font size=+1><b>SOURCE </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <tt><font size=+1>/usr/local/plan9/src/lib9<br> + /usr/local/plan9/src/libsec/port<br> + </font></tt> +</table> +<p><font size=+1><b>SEE ALSO </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <a href="../man3/mp.html"><i>mp</i>(3)</a><br> + +</table> +<p><font size=+1><b>BUGS </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <i>Truerand</i> and <i>ntruerand</i> maintain a static file descriptor. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + To avoid name conflicts with the underlying system, <i>rand</i>, <i>lrand</i>, + <i>frand</i>, <i>nrand</i>, <i>lnrand</i>, and <i>srand</i> are preprocessor macros defined + as <i>p9rand</i>, <i>p9lrand</i>, and so on; see <a href="../man3/intro.html"><i>intro</i>(3)</a>.<br> + +</table> + +<td width=20> +<tr height=20><td> +</table> +<!-- TRAILER --> +<table border=0 cellpadding=0 cellspacing=0 width=100%> +<tr height=15><td width=10><td><td width=10> +<tr><td><td> +<center> +<a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a> +</center> +</table> +<!-- TRAILER --> +</body></html> |