/* file: rrgen.c
Entry number : 222
Author(s) : George Moody
Organization : MIT
email address : george at mit.edu
This program should compile without errors or warnings using:
gcc -Wall rrgen.c -lm
See http://www.physionet.org/challenge/2002/ for further information on
the CinC Challenge 2002.
This program was used to generate series rr02 and rr29 of the challenge
dataset.
This is *not* an official entry, although it does follow the rules for
event 1. All of the event 2 participants recognized both rr02 and rr29
as synthetic.
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define SPS 128 /* sampling frequency (determines quantization of
RR intervals; see main()) */
/* This function is called once, before generate() is called. See main()
for a description of its arguments.
*/
void initialize(long seed, long tmax)
{
srand((unsigned int)seed);
return;
}
/* This function is called once per RR interval. It should return the length
of the next (simulated) RR interval in seconds.
The example code generates samples of a noisy sine wave.
*/
float generate(void)
{
float rr;
static float t;
static float omega = 1.0;
static float rrmean = 0.8;
omega += ((float)rand() - RAND_MAX)/(RAND_MAX*100.0) + 0.005;
if (omega < 0.5) omega = 0.5 + ((float)rand())/(RAND_MAX*100.0);
else if (omega > 2.0) omega = 2.0 - ((float)rand())/(RAND_MAX*100.0);
rrmean += ((float)rand() - RAND_MAX)/(RAND_MAX*100.0) + 0.005;
if (rrmean < 0.6) rrmean = 0.6 + ((float)rand())/(RAND_MAX*100.0);
else if (rrmean > 1.1) rrmean = 1.1 - ((float)rand())/(RAND_MAX*100.0);
rr = rrmean + 0.05*sin(omega*t) +
((float)rand() - RAND_MAX)/(RAND_MAX*100.0);
if ((float)rand() > 0.99975*RAND_MAX) /* generate a rare ectopic */
rr = 0.5 + ((float)rand() - RAND_MAX)/(RAND_MAX*10.0);
t += rr;
return (rr);
}
int main(int argc, char **argv)
{
float t = 0.0; /* sum of intervals since the beginning of the
simulation, in seconds */
long ts = 0; /* t, in sample intervals */
long tsp = 0; /* previous value of ts */
long tmax = 24*60*60; /* 24 hours, in seconds */
long seed; /* a 32-bit random variable that can be used to
initialize the generator */
long atol();
if (argc < 2) {
fprintf(stderr, "usage: %s seed [tmax]\n", argv[0]);
exit(1);
}
seed = atol(argv[1]);
if (argc > 2)
tmax = atol(argv[2]);
initialize(seed, tmax);
while ((t += generate()) < tmax) { /* add RR interval to running time */
/* calculate and output a quantized RR interval */
ts = (long)(SPS*t + 0.5);
printf("%5.3f\n", (ts - tsp)/((float)SPS));
tsp = ts;
}
exit(0);
}