Trapezoidal rule for loop

So i have done the calculation for only one value of n = 200. The code that i have written is :

f = @(x)6*(cos(x/2)) .* (sin(x/2)).^2;   % Defining given function
a = 0; % lower limit
b = pi; % upper limit
n = 200;   % Number of intervals
h = (b-a)/n;   % Width of each interval
s = 1/2 * (f(a) + f(b));   % Summation value
% make for loops to calculate values between the intervals
for i = 1 : n-1
    s = s + f(a + i*h);
end
A = h * s;   % The calcuated sum of all intervals
format long   % Make the outcome to be in long format
disp(A)   % Display the outcome

However now that i'm trying to make the loop for values of n = 20 , 50 , 100 , 150, 400. But im struggling to adjust the above code. any help is very appreciated.

Answer 1

[Geoff Hayes]

Nima - perhaps try

for n = [20,50,100,150,400]
    f = @(x)6*(cos(x/2)) .* (sin(x/2)).^2;   % Defining given function
    a = 0; % lower limit
    b = pi; % upper limit
    h = (b-a)/n;   % Width of each interval
    s = 1/2 * (f(a) + f(b));   % Summation value
    % make for loops to calculate values between the intervals
    for i = 1 : n-1
        s = s + f(a + i*h);
    end
    A = h * s;   % The calcuated sum of all intervals
    format long   % Make the outcome to be in long format
    fprintf('n = %d value=%f\n', n, A);   % Display the outcome
end

I've replaced the call to display with fprintf to write out the value of n and A.

[Katerin]

I have the similar code in Matlab, but I have to implement errors between each step.

It should be sth like error1=abs(outcome1-outcome2); error2=abs(outcome2-outcome3) and so on..

I am pretty desperate so any help would be appreciated.