feynlag.vacuum.diagonalize.diagonalize_takagi¶

feynlag.vacuum.diagonalize.diagonalize_takagi(M, old_fields=None, new_fields=None)[source]¶

Takagi factorization of a (real) symmetric Majorana mass matrix.

Returns (U, D) with M = U D Uᵀ and D diagonal non-negative: a real orthogonal diagonalization with factors of i absorbing negative eigenvalues (the standard Majorana phase convention).

If old_fields/new_fields are given, also returns the corresponding unitary Rotation (new = U† old) as third element.