how to make a plot from my function results?

How to make a plot from my function results?

(My function finds pi_aprox with a method and calculates the error from pi every time,it calculate for n times) i want to plot (error) and (n). From that plot we will see that inreasing n the error will be decreased.

[Alireza Ghaderi]

simply create a variable called error... on each row store the new function output. then the row number is associated with the n.

then plot(error,n)

[Chris ch]

Ty for your answer , cause i am new in matlab ,how to write this ?

Answer 1

[the cyclist]

Here is an example using a for loop that calculates and plots the Gregory-Leibinz approximation to pi:

n_max = 100;

pi_approx = zeros(n_max,1);
pi_approx(1) = 4/1;

for n = 2:n_max
    factor = (-1)^(n-1) / (2*n - 1);
    pi_approx(n) = pi_approx(n-1) + 4*factor;
end

figure
plot(1:n_max,pi_approx - pi)

Here is an equivalent vectorized version:

n = 1:100;
factor = 4 * (-1).^(n-1) ./ (2*n - 1);
pi_approx = cumsum(factor);

figure
plot(1:n_max,pi_approx - pi)