function A = coef(alpha)
   % Do not change the function name, number of input and output variables.
   % In this function you have to calculate the coef. A0 to A20 using integrations.
   % The input is only the angle of attack in radian, and the output is a vector array
   % with 21 elements. The first element is A0, and the last element is A20.
   % Note that this function and dcamber do not need the chord length.
   theta = 0:pi()/21:pi();
   A = zeros(21,1);
   dzdx = @(theta) dcamber(theta);
   A(1) = alpha - 1/pi*integral(dzdx, 0, pi);
   for i = 1:1:20
       fun2 = @(theta2) dcamber(theta2).*cos(i.*theta2);
       A(i+1) = 2/pi*integral(fun2, 0, pi);
   end

   % Write a loop that goes over the calculation of each element of A using the dz/dx
   % defined in dcamber function.
   % Remember that some functions are defined using the auxiliary variable theta, and
   % some are based on x/c and z/c.
   % Use any integration method you like. But, you may need to increase the accuracy
   % to be able to generate the same coef. as the reference code.
end

function dzdx = dcamber(theta)
xc = (1/2) .* (1-cos(theta))
zc = zeros(1,21);
i=1;
   while xc(i)<=0.2025
       zc(i) = 2.6595*xc(i)*(xc(i)^2 - 0.6075*xc(i) + 0.1147);
       i = i+1;
   end
   while i<=21
       zc(i) = 0.02208*(1-xc(i));
       i = i+1;
   end
   dzdx = zeros(1,21);
    i=1;
   while xc(i)<=0.2025
       dzdx(i) = (2.6595*(3*(xc(i)^2) - 1.2150*xc(i) + 0.1147));
       i = i+1;
   end
   while i<=21
       dzdx(i) = -0.02208;
       i = i+1;
   end
   % write a function that calculates dz/dx for each value of theta. You may want to
   % create a function that works with a vector array as theta and generates a vector
   % array dzdx corresponding to each element of input.
end