me.
y : ndarray, shape (n,)
    Current state.
f : ndarray, shape (n,)
    Value of the right hand side at (t, y).
threshold : float
    Threshold for `y` value used for computing the step size as
    ``factor * np.maximum(np.abs(y), threshold)``. Typically, the value of
    absolute tolerance (atol) for a solver should be passed as `threshold`.
factor : ndarray with shape (n,) or None
    Factor to use for computing the step size. Pass None for the very
    evaluation, then use the value returned from this function.
sparsity : tuple (structure, groups) or None
    Sparsity structure of the Jacobian, `structure` must be csc_matrix.

Returns
-------
J : ndarray or csc_matrix, shape (n, n)
    Jacobian matrix.
factor : ndarray, shape (n,)
    Suggested `factor` for the next evaluation.
r