bladex.ndinterpolator.RBF.inv_multi_quadratic_biharmonic_spline¶

static RBF.inv_multi_quadratic_biharmonic_spline(X, r)[source]¶

It implements the following formula:

$\varphi(\| \boldsymbol{x} \|) = (\| \boldsymbol{x} \|^2 + r^2 )^{-\frac{1}{2}}$

Parameters:	X (numpy.ndarray) – l2-norm between given inputs of a function and the locations to perform rbf approximation to that function. r (float) – smoothing length, also called the cut-off radius.
Returns:	result: the result of the formula above.
Return type:	float