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

# include "cnoise.h"

/*
 * This is example code for how to call functions from the cnoise library.
 * We generate M realizations of size N of noise
 * With std = 1 and M >= 10000, for cnoise_generate_colored_noise(...) you should get
 * expected value for the mean to be close to zero and the standard deviation should
 * vary linearly in alpha with 1 for alpha = 0 and 0.575 for alpha = 2.
 * Note that the values are approximate.
 * 
*/


double mean ( double *x, int N ){
	int i;
	double mean = 0.0;
	for( i=0; i<N; i++ ){ mean += x[i]; };
	return ( mean / ( (double) N ) );
};

void mean_std ( double *x, int N, double *mean, double *std ){
	int i;
	*mean = 0.0;
	for( i=0; i<N; i++ ){ *mean += x[i]; };
	*mean /= (double) N;
	
	*std = 0.0;
	for( i=0; i<N; i++ ){ *std += ( x[i] - *mean ) * (x[i] - *mean ); };
	*std = sqrt( *std /( (double) (N-1) )  );
};

int main ( int argc, char ** argv ){
	
	double std = 1.0;
	double alpha = 1.0;
	double range = 1.0;
	int N = 10000;
	int M = 10000;
	
	int i,j;
	double scale = exp( 0.5*(1-alpha) * log( N ) );
	double *x = malloc( N * sizeof( double ) );
	double *res = malloc( M * sizeof( double ) );
	double result_mean, result_std;
/*
  Make sure to call srand() in your program before you call any of the cnoise_* functions
*/
	srand ( time(0) ); 
	
	for( i=0; i<M; i++ ){
		cnoise_generate_colored_noise ( x, N, alpha, std );
		//cnoise_generate_colored_noise_uniform( x, N, alpha, range );
		//cnoise_generate_colored_noise_truncated( x, N, alpha, std, range );
		for( j=0; j<N; j++ ){
			x[j] *= scale;
		};
		res[i] = mean( x, N );
	};
	
	mean_std ( res, M, &result_mean, &result_std );
		
	printf ( " Alpha = %f  Std = %f  Range = %f  M = %d  N = %d \n",alpha,std,range,M,N );
	
	printf ( "   Expected value of the mean %f  Standard deviation %f \n", result_mean, result_std );
	
	free ( res );
	free ( x );
	
	return 0;
};