You have to change your code to add a counter:
x = 4;
finalroot = 2.72;
diff = 1;
k1 = 1;
while diff > 0.5e-7
xlast = x;
x = xlast - f(xlast)/fd(xlast);
diff = abs(x - xlast);
e(k1) = abs(finalroot - x);
fprintf('%1.8f\n',e(k1))
k1 = k1 + 1;
end
The initial ‘k1’ assignment initialises the counter, then it is incremented after the ‘e(k1)’ assignment in every iteration of the loop. (It also keeps track of the number of iterations if you need to access that information.)
