Issue with the compute_joint_velocity fonctions

[KALrious]

Hi, I got a issue every time I'm trying to compute_joint_velocity from one robot.
I am a student in University of Wollongong in Australia and we have to use ARTE for one of our project in lecture.
I built a new robot and I got an issue with the functions compute_joint_volocity it tell me that:
"Undefined function or variable 'manipulator_jacobian'.

Error in compute_joint_velocity (line 55)
J = manipulator_jacobian(robot, q);

Error in question10partB (line 41)
vq = compute_joint_velocity(robot, q(:,1), V/norm(V)');"

I will really appreciate if you can help me