You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: roty.m
    path of file: ./repos/whole-body-controllers/library/matlab-wbc/+wbc
    
    the code of the file until where you have to start completion: function R = roty(alpha)

    
function R = roty(alpha)

    % ROTY computes a rotation along the y axis (rotation matrix).
    %
    % FORMAT: R = roty(alpha)     
    %
    % INPUT:  - alpha = angle in radians
    %
    % OUTPUT: - R = [3 * 3] rotation matrix along y axis
    %
    % Authors: Daniele Pucci, Marie Charbonneau, Gabriele Nava
    %          
    %          all authors are with the Italian Istitute of Technology (IIT)
    %          email: name.surname@iit.it
    %
    % Genoa, Dec 2017
    %

    %% --- Initialization ---

   R = [cos(alpha), 0, sin(alpha);
        0, 1, 0;
        -sin(alpha), 0, cos(alpha)];

end