spd_learn.functional.untangent_space#

spd_learn.functional.untangent_space(T, Cref, *, metric='riemann')[source]#

Transform tangent vectors back to matrices.

Transform tangent vectors back to matrices, according to a reference matrix Cref and to a specific exponential map.

Parameters:

  • T (ndarray, shape (..., n * (n + 1) / 2)) – Tangent vectors.

  • Cref (ndarray, shape (n, n)) – Reference matrix.

  • metric (string | callable, default="riemann") – Metric used for exponential map, can be: “euclid”, “logchol”, “logeuclid”, “riemann”, “wasserstein”, or a callable function.

Returns:

X – Matrices in manifold.

Return type:

ndarray, shape (…, n, n)

Notes

Changed in version 0.12.

See also

unupper, exp_map