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Add eigentune calculation to MATRIX_Lattice #151

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Add eigentune calculation to MATRIX_Lattice #151

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16 changes: 15 additions & 1 deletion py/orbit/matrix_lattice/MATRIX_Lattice.py
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@
"""
import os
import math

import numpy as np

# import bunch
from orbit.core.bunch import Bunch
Expand Down Expand Up @@ -112,6 +112,8 @@ def getRingParametersDict(self, momentum, mass):
mt = self.oneTurnMatrix
res_dict["fractional tune x"] = None
res_dict["fractional tune y"] = None
res_dict["fractional tune 1"] = None
res_dict["fractional tune 2"] = None
res_dict["alpha x"] = None
res_dict["alpha y"] = None
res_dict["beta x [m]"] = None
Expand All @@ -138,6 +140,18 @@ def getRingParametersDict(self, momentum, mass):
nuy = math.acos(cos_phi_y) / (2 * math.pi) * sign_y
res_dict["fractional tune x"] = nux
res_dict["fractional tune y"] = nuy

# Eigentunes
M = np.array([[mt.get(i, j) for j in range(4)] for i in range(4)])
eigvals, _ = np.linalg.eig(M)
eigvals = eigvals[[0, 2]]
cos_phi = np.real(eigvals)
phi = np.arccos(cos_phi)
nu = phi / (2.0 * np.pi)
nu %= 1.0
res_dict["fractional tune 1"] = float(nu[0])
res_dict["fractional tune 2"] = float(nu[1])

# alpha, beta, gamma
beta_x = mt.get(0, 1) / sin_phi_x
beta_y = mt.get(2, 3) / sin_phi_y
Expand Down
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