>>> np.set_printoptions(precision=4)
>>> np.lib.scimath.arctanh([1j])
array([ 0.+0.7854j])
so far, so good
>>> np.lib.scimath.arctanh(1j)
0.78539816339744828j
i.e., set_printoptions didn't affect the result when the input was a scalar. "Feature" or bug?
DG