two exercises from Sedgewick's Algorithms in C

gistfile1.c

/* exercises, chapter 3, section 1 */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <limits.h>
#include <float.h>
#include <math.h>
#include <gsl/gsl_math.h>
#include <gsl/gsl_rng.h>
#include <gsl/gsl_randist.h>

#define ARRAY_SIZE(x)  (sizeof(x) / sizeof(x[0]))

gsl_rng * r;

void exercise_3_1_1() {
	printf("minimum int: %d\n", INT_MIN);
	printf("maximum int: %d\n\n", INT_MAX);
	
	printf("minimum long int: %ld\n", LONG_MIN);
	printf("maximum long int: %ld\n\n", LONG_MAX);
	
	printf("minimum short int: %d\n", SHRT_MIN);
	printf("maximum short int: %d\n\n", SHRT_MAX);
	
	printf("minimum float: %e\n", -FLT_MAX);
	printf("maximum float: %e\n\n", FLT_MAX);
	
	printf("minimum double: %e\n", -DBL_MAX);
	printf("maximum double: %e\n\n", DBL_MAX);

	printf("minimum long double: %Lg\n", -LDBL_MAX);
	printf("maximum long double: %Lg\n", LDBL_MAX);
}


int random_integer_system(int max) {
	return gsl_rng_uniform_int(r, max);
}


void exercise_3_1_2() {
	gsl_rng_env_setup();
	r = gsl_rng_alloc (gsl_rng_default);
	
	gsl_rng_set(r, time(NULL));

	int maxes[] = {10, 100, 1000};
	int counts[] = {1000, 10000, 100000, 1000000, 10000000, 100000000};

	for(int max_idx = 0; max_idx < ARRAY_SIZE(maxes); max_idx++) {
		for(int count_idx = 0; count_idx < ARRAY_SIZE(counts); count_idx++) {
			int max = maxes[max_idx];
			int count = counts[count_idx];

			int random_integer = 0;

			double moment1 = 0.0;
			double moment2 = 0.0;

			for(int i = 0; i < count; i++) {
				random_integer = random_integer_system(max);
				moment1 += ((double) random_integer)/count;
				moment2 += ((double) random_integer*random_integer)/count;
			}

			double standard_deviation = sqrt(moment2 - moment1*moment1);

			printf("For 0-%d, count = %d: average = %f, standard deviation = %f\n", max-1, count, moment1, standard_deviation);
		}
	}

	gsl_rng_free (r);
}

int main() {
	exercise_3_1_2();


	return 0;
}