randomWH_usage.c

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#include <stdio.h>
#include <stdlib.h>


#include "randomWH.h"
#define SIM_DURATION 40000000L

/* Example of struct initialisation
 * A struct called congruent is pre-initialised for you
 */

Congruence congruent2={
    .x=0,
    .y=0,
    .z=0,
    .t=0,
    .initialised=isfalse,
    .init=Congruence_init,
    .randomWH=randomWH_null,
    .read=Congruence_read,
    .bernoulli=randomWH_bernoulli,
    .geometric=randomWH_geometric,
    .binomial=randomWH_binomial,
    .fairdie=randomWH_fairdie,
};

void Congruence_dump(Congruence* generatorZ);

void Congruence_dump(Congruence* generatorZ){
    long int* read_con;
    int count;
    char seednames[]={'x','y','z','t'};
    read_con=generatorZ->read(generatorZ);
    for(count=0;count<4;count++)
        printf("seed %c = %ldL\n", seednames[count], read_con[count]);
}


int main(){
    long int count;
    double mean=0, moment2=0, unif, variance, prob;
    Congruence* sequence = &congruent2;
/* Generate a sequence and calculate its first and second moment */
    congruent.init(&congruent,1L,2L,3L,4L);
    for(count =0;count<SIM_DURATION;count++){
        unif = congruent.randomWH(&congruent);
        mean += unif;
        moment2 += (unif*unif);
    }
    mean /= SIM_DURATION;
    moment2 /= (SIM_DURATION-1.0); /* using Bessel's correction */
    variance = moment2-mean*mean*(SIM_DURATION)/(SIM_DURATION-1.0); /* Bessel's correction continued */
    printf("Mean after %ld iterations is %lf; sample variance is %lf\n", SIM_DURATION, mean, variance);
    printf("Seeds to use for next run:\n");
    Congruence_dump(&congruent);

    printf("\n");

/* Generate the same sequence, using a second instance of the generator */
    mean = moment2 = 0;
    sequence->init(sequence, 1L,2L,3L,4L);
    for(count =0;count<SIM_DURATION;count++){
        unif = sequence->randomWH(sequence);
        mean += unif;
        moment2 += (unif*unif);
    }
    mean /= SIM_DURATION;
    moment2 /= (SIM_DURATION-1.0); /* using Bessel's correction */
    variance = moment2-mean*mean*(SIM_DURATION)/(SIM_DURATION-1.0); /* Bessel's correction continued */
    printf("Mean after %ld iterations is %lf; sample variance is %lf\n", SIM_DURATION, mean, variance);
    printf("Seeds to use for next run:\n");
    Congruence_dump(sequence);

/* Estimate means of some distributions */
    prob = 0.1;
    mean = 0.0;
    for(count = 1;count<=50000;count++)
        mean += congruent.geometric(&congruent,prob);
    printf("\nMean number of tries until first success, each trial with probability %lf: %lf\n"
           ,prob,mean/(count-1));
    prob=0.5;
    mean = 0.0;
    for(count = 1;count<=50000;count++)
        mean += congruent.bernoulli(&congruent,prob)==istrue?1:-1;
    printf("\n%ld fair coin tosses: Mean: %lf (should approach zero)\n",count-1,mean/(count-1));
    prob = 0.666666666666666666;
    mean = 0.0;
    for(count = 1;count<=50000;count++)
        mean += congruent.binomial(&congruent,30L,prob);
    printf("\nMean number of successes in 30 trials with prob. of success %lf is %lf", prob, mean/(count-1));
    printf("\n");

    mean = 0.0;
    for(count = 1;count<=50000;count++)
        mean += congruent.fairdie(&congruent,1L,6L);
    printf("\nMean result of %ld dice throws: %lf", count-1, mean/(count-1));
    printf("\n");

    return EXIT_SUCCESS;
}