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: slaccel.m
    path of file: ./repos/Robotics-Toolbox/rvctools/release10.3.1/simulink
    
    the code of the file until where you have to start completion: %SLACCEL	S-function for robot ac
    
function for robot acceleration
%
% This is the S-function for computing robot acceleration. It assumes input
% data u to be the vector [q qd tau].
%
% Implemented as an S-function to get around vector sizing problem with
% Simulink 4.

function [sys, x0, str, ts] = slaccel(t, x, u, flag, robot)
	switch flag

	case 0
		% initialize the robot graphics
		[sys,x0,str,ts] = mdlInitializeSizes(robot);	% Init

	case {3}
		% come here to calculate derivitives
        
        % first check that the torque vector is sensible
        assert(numel(u) == (3*robot.n), 'RTB:slaccel:badarg', 'Input vector is length %d, should be %d', numel(u), 3*robot.n);
        assert(isreal(u), 'RTB:slaccel:badarg', 'Input vector is complex, should be real'); 
        
		sys = robot.accel(u(:)');
        
	case {1, 2, 4, 9}
		sys = [];
	end