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/*
* Paretoormal distribution table generator
*
* This distribution is simply .25*normal + .75*pareto; a combination
* which seems to match experimentally observed distributions reasonably
* well, but is computationally easy to handle.
* The entries represent a scaled inverse of the cumulative distribution
* function.
*
* Taken from the uncopyrighted NISTnet code.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <limits.h>
#include <malloc.h>
#include <linux/types.h>
#include <linux/pkt_sched.h>
#define TABLESIZE 16384
#define TABLEFACTOR NETEM_DIST_SCALE
static double
normal(double x, double mu, double sigma)
{
return .5 + .5*erf((x-mu)/(sqrt(2.0)*sigma));
}
static const double a=3.0;
static int
paretovalue(int i)
{
double dvalue;
i = 65536-4*i;
dvalue = (double)i/(double)65536;
dvalue = 1.0/pow(dvalue, 1.0/a);
dvalue -= 1.5;
dvalue *= (4.0/3.0)*(double)TABLEFACTOR;
if (dvalue > 32767)
dvalue = 32767;
return (int)rint(dvalue);
}
int
main(int argc, char **argv)
{
int i,n;
double x;
double table[TABLESIZE+1];
for (x = -10.0; x < 10.05; x += .00005) {
i = rint(TABLESIZE*normal(x, 0.0, 1.0));
table[i] = x;
}
printf(
"# This is the distribution table for the paretonormal distribution.\n"
);
for (i = n = 0; i < TABLESIZE; i += 4) {
int normvalue, parvalue, value;
normvalue = (int) rint(table[i]*TABLEFACTOR);
parvalue = paretovalue(i);
value = (normvalue+3*parvalue)/4;
if (value < SHRT_MIN) value = SHRT_MIN;
if (value > SHRT_MAX) value = SHRT_MAX;
printf(" %d", value);
if (++n == 8) {
putchar('\n');
n = 0;
}
}
return 0;
}
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