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

#define NITER 20

double TaylorLog(double);
void WriteDifference(double diff[]);

main(){

	printf("Qui va la descrizione del programma\n\n");
	
	int i;
	double x, AppLog, difference[NITER];
	
	int seed;
	seed=time(0);
	srand48(seed);
	
	for(i=0;i<NITER;i++){
		
		x=(double)(2.*lrand48()-RAND_MAX)/(RAND_MAX+1.);
		AppLog=TaylorLog(x);
		difference[i]=log(1.+x)-AppLog;
		
	}
	
	WriteDifference(difference);
	
}

double TaylorLog(double y){

	double approx;
	
	approx=y-0.5*pow(y,2.)+pow(y,3.)/3.-0.25*pow(y,4);
	
	return approx;
	
}

void WriteDifference(double data[]){

	int k;
	
	FILE *Write;
	
	Write=fopen("diff.dat","w");
	
	for(k=0;k<NITER;k++){
		fprintf(Write,"%d  %lf \n",k,*(data+k));
	}
	
	fclose(Write);

}