import numpy as np
from UQpy.utilities.distances.baseclass.GrassmannianDistance import (
GrassmannianDistance,
)
from UQpy.utilities.GrassmannPoint import GrassmannPoint
[docs]class FubiniStudyDistance(GrassmannianDistance):
"""
A class to calculate the Fubini-Study distance between two Grassmann points.
"""
[docs] def compute_distance(self, xi: GrassmannPoint, xj: GrassmannPoint) -> float:
"""
Compute the Fubini-Study distance between two points on the Grassmann manifold.
:param xi: Orthonormal matrix representing the first point.
:param xj: Orthonormal matrix representing the second point.
"""
GrassmannianDistance.check_rows(xi, xj)
r = np.dot(xi.data.T, xj.data)
(ui, si, vi) = np.linalg.svd(r, full_matrices=True)
index = np.where(si > 1)
si[index] = 1.0
theta = np.arccos(si)
cos_t = np.cos(theta)
distance = np.arccos(np.prod(cos_t))
return distance