'Evaluate the spline at points
Returns the interpolated value at ``(xi[i], yi[i]),
i=0,...,len(xi)-1``.
Parameters
xi, yi : array_like
Input coordinates. Standard Numpy broadcasting is obeyed.
dx : int, optional
Order of x-derivative
.. versionadded:: 0.14.0
dy : int, optional
Order of y-derivative
.. versionadded:: 0.14.0'

def ev(self, xi, yi, dx=0, dy=0):

    return self.__call__(xi, yi, dx=dx, dy=dy, grid=False)
