*args : arrays
x, y, z, ..., d, where x, y, z, ... are the coordinates of the nodes
and d is the array of values at the nodes
function : str or callable, optional
The radial basis function, based on the radius, r, given by the norm
(defult is Euclidean distance); the default is ‘multiquadric’:
'multiquadric': sqrt((r/self.epsilon)**2 + 1)
'inverse': 1.0/sqrt((r/self.epsilon)**2 + 1)
'thin_plate': r**2 * log(r)
If callable, then it must take 2 arguments (self, r). The epsilon
parameter will be available as self.epsilon. Other keyword
arguments passed in will be available as well.
epsilon : float, optional
Adjustable constant for gaussian or multiquadrics functions
- defaults to approximate average distance between nodes (which is
a good start).
smooth : float, optional
Values greater than zero increase the smoothness of the
approximation. 0 is for interpolation (default), the function will
always go through the nodal points in this case.
norm : callable, optional
A function that returns the ‘distance’ between two points, with
inputs as arrays of positions (x, y, z, ...), and an output as an
array of distance. E.g, the default:
def euclidean_norm(x1, x2):
return sqrt( ((x1 - x2)**2).sum(axis=0) )
which is called with x1=x1[ndims,newaxis,:] and
x2=x2[ndims,:,newaxis] such that the result is a matrix of the
distances from each point in x1 to each point in x2.