Costs returns the list [array(5.801),array(nan)] instead of the list [array(5.801),array(0.310)]

I getting cost by taking: grads, cost and equaling it to the propagate function

Example:

<grads, cost = propagate(w, b, X, Y)>

The propagate function already passed all tests, and the only way I could think of a potential error is with the cost equation supposed to be using np.dot instead of the element wise multiplication I was using, but if np.dot was used for matrix multiplication A having shape (1,3) and Y having shape (1,3) would cause an error.