| /* |
| * 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; |
| } |