`scl` (the
scaling factor is for use in a linear change of variable). The argument
`c` is an array of coefficients from low to high degree along each
axis, e.g., [1,2,3] represents the series ``1*He_0 + 2*He_1 + 3*He_2``
while [[1,2],[1,2]] represents ``1*He_0(x)*He_0(y) + 1*He_1(x)*He_0(y)
+ 2*He_0(x)*He_1(y) + 2*He_1(x)*He_1(y)`` if axis=0 is ``x`` and axis=1
is ``y``.

Parameters
----------
c : array_like
    Array of Hermite_e series coefficients. If `c` is multidimensional
    the different axis correspond to different variables with the
    degree in each axis given by the corresponding index.
m : int, optional
    Number of derivatives taken, must be non-negative. (Default: 1)
scl : scalar, optional
    Each differentiation is multiplied by `scl`.  The end result is
    multiplication by ``scl**m``.  This is for use in a linear change of
    variable. (Default: 1)
axis : int, optional
    Axis over which the derivative is taken. (Default: 0).

Returns
-------
der : ndarray
    Hermite series of the derivative.

See Also
--------
hermeint

Notes
-----
In general, the result of differentiating a Hermite series does not
resemble the same operation on a power series. Thus the result of this
function may be "unintuitive," albeit correct; see Examples section
below.

Examples
--------
>>> from numpy.polynomial.hermite_e import hermeder
>>> hermeder([ 1.,  1.,  1.,  1.])
array([1.,  2.,  3.])
>>> hermeder([-0.25,  1.,  1./2.,  1./3.,  1./4 ], m=2)
array([1.,  2.,  3.])

r