(TAREFA 3) Int I

// calcular numericamente int_{0.1}^{1.0} (1/x)dx = -ln(0.1)
// calcular pela regra retangular

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

#define n 1000

int main(void)
{
  int i;
  double h,x,sum=0.0,val,e;

  h=(1.0-0.1)/n;

  for (i=1;i<=n;i++)
    {
      x=0.1+h*i;
      sum+=h*(1/x);
    }

  val=-log(0.1);
  e=((val-sum)/val)*100;

  printf("Valor calculado: %lf\n",sum);
  printf("Valor real: %lf\n",val);
  printf(