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?RCS: $Id: randfunc.U 167 2013-05-08 17:58:00Z rmanfredi $
?RCS:
?RCS: Copyright (c) 1991-1997, 2004-2006, Raphael Manfredi
?RCS:
?RCS: You may redistribute only under the terms of the Artistic License,
?RCS: as specified in the README file that comes with the distribution.
?RCS: You may reuse parts of this distribution only within the terms of
?RCS: that same Artistic License; a copy of which may be found at the root
?RCS: of the source tree for dist 4.0.
?RCS:
?RCS: $Log: randfunc.U,v $
?RCS: Revision 3.0 1993/08/18 12:09:39 ram
?RCS: Baseline for dist 3.0 netwide release.
?RCS:
?X:
?X: This is the new unit that should be used when random
?X: functions are to be used. It thus makes randbits.U obsolete.
?X:
?MAKE:randfunc mrand seedfunc nrandbits: cat +cc rm test Myread Csym
?MAKE: -pick add $@ %<
?S:randfunc:
?S: Indicates the name of the random number function to use.
?S: Values include drand48, random, and rand. In C programs,
?S: the 'nrand' macro is defined to generate uniformly distributed
?S: random numbers over the range [0., 1.] (see mrand and nrand).
?S:.
?S:mrand:
?S: Indicates the macro to be used to generate normalized
?S: random numbers. Uses randfunc, often divided by
?S: (double) ((1 << nrandbits) -1) in order to normalize the result.
?S: In C programs, the macro 'nrand' is maped on mrand.
?S:.
?S:seedfunc:
?S: Indicates the random number generating seed function.
?S: Values include srand48, srandom, and srand.
?S:.
?S:nrandbits:
?S: Indicates how many bits are produced by the function used to
?S: generate normalized random numbers.
?S:.
?C:nrand:
?C: This macro is to be used to generate uniformly distributed
?C: random numbers over the range [0., 1.].
?C:.
?C:seednrand:
?C: This symbol defines the macro to be used in seeding the
?C: random number generator (see nrand).
?C:.
?H:#define nrand() $mrand /**/
?H:#define seednrand(x) $seedfunc(x) /**/
?H:.
?T:cont val
?LINT:nothere $nrandbits)
: How can we generate normalized random numbers ?
echo " "
case "$randfunc" in
'')
if set drand48 val -f; eval $csym; $val; then
dflt="drand48"
echo "Good, found drand48()." >&4
elif set random val -f; eval $csym; $val; then
dflt="random"
echo "OK, found random()." >&4
else
dflt="rand"
echo "Yick, looks like I have to use rand()." >&4
fi
echo " "
;;
*)
dflt="$randfunc"
;;
esac
cont=true
while $test "$cont"; do
rp="Use which function to generate random numbers?"
. ./myread
?X: Invalidates nrandbits if the answer is not the default so
?X: that the value stored in config.sh will not be used when
?X: we change our random function.
if $test "$ans" = "$dflt"; then
: null
else
nrandbits=''
fi
randfunc="$ans"
if set $ans val -f; eval $csym; $val; then
cont=''
else
dflt=n
rp="Function $ans does not exists. Use that name anyway?"
. ./myread
dflt=rand
case "$ans" in
[yY]*) cont='';;
esac
fi
case "$cont" in
'')
case "$randfunc" in
drand48)
mrand="drand48()"
seedfunc="srand48"
;;
rand*)
case "$nrandbits" in
'')
echo "Checking to see how many bits your $randfunc() function produces..." >&4
$cat >try.c <<EOCP
#include <stdio.h>
int main()
{
register int i;
register unsigned long tmp;
register unsigned long max = 0L;
extern long random();
for (i = 1000; i; i--) {
tmp = (unsigned long)$randfunc();
if (tmp > max) max = tmp;
}
for (i = 0; max; i++)
max /= 2;
printf("%d\n",i);
}
EOCP
if $cc -o try try.c >/dev/null 2>&1 ; then
dflt=`try`
else
dflt='?'
echo "(I can't seem to compile the test program...)"
fi
;;
*)
dflt="$nrandbits"
;;
esac
rp="How many bits does your $randfunc() function produce?"
. ./myread
nrandbits="$ans"
$rm -f try.c try
mrand="($randfunc() / (double) ((1 << $nrandbits) -1))"
seedfunc="srand"
;;
?X: The following is provided just in case...
*)
dflt="31"
rp="How many bits does your $randfunc() function produce?"
. ./myread
nrandbits="$ans"
seedfunc="s$randfunc"
mrand="($randfunc() / (double) ((1 << $nrandbits) -1))"
if set $seedfunc val -f; eval $csym; $val; then
echo "(Using $seedfunc() to seed random generator)"
else
echo "(Warning: no $seedfunc() to seed random generator)"
seedfunc=rand
fi
;;
esac
;;
esac
done
|
