I am new to Pennylane so please forgive the naivete of my question. You seem to be using autograd, but you also use this nice trick of evaluating derivatives of Rx, Ry, Rz at theta with an explicitly formula. I’ve never used autograd before. I assume it complains when you use a function of bumpy that is unsupported. So why the explicit formula? Does autograd complain about something that the explicit formula circumvents? When does autograd need help in taking the derivative of a Variable of Pennylane?

You seem to create your own dag which exists at the same time as the dag that autograd creates. Is that correct? When you do backprop to calculate the grads, do you use your dag or autograd’s