hgrlk - store each value of x from each iteration of your loop. Then, when the loop concludes, you can plot the data. Perhaps somethig like
Ea = 100;
maxIterations = 50;
m = 1;
x = zeros(maxIterations,1);
x(m) = 12;
f = @(x) x.^3 - x - 3 ;
diff = @(x) 3*(x.^2) - 1 ;
while abs(Ea) > 10^(-3) && m < maxIterations
xnew = x(m) - (f(x(m)) / diff(x(m)));
Ea = (((xnew-x(m))/xnew)*100);
fprintf('%d %10.4f %10.4f %10.4f %10.4f\n',m,x(m),f(x(m)),diff(x(m)),abs(Ea));
m = m + 1;
x(m) = xnew;
end
x = x(1:m);
figure;
plot(x);
figure;
plot(f(x));
Note how we combine the two conditions that you have - that for the error and that for the maximum number of iterations. The f and diff are defined outside of the while loop since we can then have access to f when we plot (once complete). On each iteration of the loop, we store the new estimate in an array so that we can plot all values of x and f(x). See plot LineSpec properties for details on how to add colour, style, and markers to your plot.
