They are much faster, as shown by this benchmark:
$ python -m timeit -s "from fdint import _fd; import numpy; x=numpy.linspace(-100,100,1000)" "_fd.fd1h(x)"
1000000 loops, best of 3: 0.29 usec per loop
$ python -m timeit -s "from fdint import fdk; import numpy; x=numpy.linspace(-100,100,1000)" "fdk(0.5, x)"
100000 loops, best of 3: 15.2 usec per loop
They are much faster, as shown by this benchmark: $ python -m timeit -s "from fdint import _fd; import numpy; x=numpy.linspace(-100,100,1000)" "_fd.fd1h(x)" 1000000 loops, best of 3: 0.29 usec per loop $ python -m timeit -s "from fdint import fdk; import numpy; x=numpy.linspace(-100,100,1000)" "fdk(0.5, x)" 100000 loops, best of 3: 15.2 usec per loop