Function k::create_reference_positions_nullspace_function

pub fn create_reference_positions_nullspace_function<T: RealField>(
    reference_positions: Vec<T>, 
    weight_vector: Vec<T>
) -> impl Fn(&[T]) -> Vec<T>

Utility function to create nullspace function using reference joint positions. This is just an example to use nullspace.

H(q) = 1/2(q-q^)T W (q-q^) dH(q) / dq = W (q-q^)

https://minus9d.hatenablog.com/entry/20120912/1347460308