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/*---------------------------------------------------------------
* Copyright (c) 2017
* Broadcom Corporation
* All Rights Reserved.
*---------------------------------------------------------------
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated
* documentation files (the "Software"), to deal in the Software
* without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute,
* sublicense, and/or sell copies of the Software, and to permit
* persons to whom the Software is furnished to do
* so, subject to the following conditions:
*
*
* Redistributions of source code must retain the above
* copyright notice, this list of conditions and
* the following disclaimers.
*
*
* Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following
* disclaimers in the documentation and/or other materials
* provided with the distribution.
*
*
* Neither the name of Broadcom Coporation,
* nor the names of its contributors may be used to endorse
* or promote products derived from this Software without
* specific prior written permission.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE CONTIBUTORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
* ________________________________________________________________
*
* pdfs.c
* Produce probability distribution functions, expected to be used
* for iperf client traffic emulations
*
* Implements the Polar form of the Box-Muller Transformation
*
* by Robert J. McMahon (rjmcmahon@rjmcmahon.com, bob.mcmahon@broadcom.com)
* & Tim Auckland
* -------------------------------------------------------------------
*/
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <math.h>
#include "headers.h"
#include "pdfs.h"
#define FALSE 0
#define TRUE 1
float box_muller(void) {
float x1, x2, w, y1;
static float y2;
static int generate = FALSE;
/* Each iteration produces two values, if one exists use the value from previous call */
generate = !generate;
if (!generate) {
y1 = y2;
} else {
int loopcontrol=100;
do {
x1 = 2.0 * (float)rand()/(float)(RAND_MAX) - 1.0;
x2 = 2.0 * (float)rand()/(float)(RAND_MAX) - 1.0;
w = x1 * x1 + x2 * x2;
} while ( w >= 1.0 && --loopcontrol > 0);
if (w >= 1.0) {
fprintf(stderr, "pdf box_muller() rand() error\n");
return 0;
} else {
w = sqrt( (-2.0 * logf( w ) ) / w );
y1 = x1 * w;
y2 = x2 * w;
}
}
return(y1);
}
float normal(float mean, float variance) {
return (box_muller() * variance + mean);
}
float lognormal(float mu, float sigma) {
float phi = sqrtf((mu * mu) + (sigma * sigma));
float mu_prime = logf(((mu * mu)/phi));
float sigma_prime = sqrtf(logf((phi * phi)/(mu * mu)));
return (expf(normal(mu_prime,sigma_prime)));
}
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