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/* Textbook standard linear congruent pseudo-random number generator
(say that ten times quick) */
/* The generator returns numbers in 0..(2**31 - 1) */
#define PERIOD 2147483647
#define T_RAND_MAX PERIOD
/* A is a "magic" constant calculated by IBM in the dawn of computing */
#define A 48271
#define Q 44488
#define R 3399
/* The seed of the generator, hopefully set by the user before rand is
called */
static int seed = 42;
/* Seeds the random number generator with the seed s */
void tsrand(unsigned int s)
{
seed = s % PERIOD;
}
/* Calculates a new random number */
int trand(void)
{
seed = A * (seed % Q) - R * (long)(seed / Q);
if(seed < 0)
seed += PERIOD;
return seed;
}
/* Bonus function, returns a random number in [0..1) */
double tfrand(void)
{
return (double)trand()/PERIOD;
}
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