func=@(x) 1/x;
a=1;
b=3;
n=7;
sum=0;
delx=(b-a)/n;
for  i=0:n;
  temp=a+(i*delx);
  temp1=func(temp);
  
  if i==0 || i==n
    sum=sum+temp;
  
  else if i/2!=0
   sum=sum+2*temp1;
 else 
   sum=sum+4*temp1;
  endif 
  endif
endfor
sum=sum*delx;
sum=sum/3;
disp(sum);