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Minor fix for error propagation and silent quad #344

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Merged
JeanLucPons merged 2 commits into from
Aug 6, 2026
Merged

Minor fix for error propagation and silent quad #344

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5cc1a61
Minor fix for error propagation
JeanLucPons Aug 6, 2026
f175f86
Fix for quad with zero strength (i.e. quadrupole corrector) that prod…
JeanLucPons Aug 6, 2026
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6 changes: 3 additions & 3 deletions pyaml/tuning_tools/bba2.py
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Original file line number Diff line number Diff line change
Expand Up @@ -99,12 +99,12 @@ def _x_intercept(x, k, n):
xx = np.polynomial.polynomial.polyfit(x[-n:], k[-n:], 1)
err = 0
if n > 2:
# Compute error on the ratio -xx[0] / xx[1]
# Compute error of the ratio r = -xx[0] / xx[1]
X = np.polynomial.polynomial.polyvander(x[-n:], 1)
R = k[-n:] - X @ xx
S2 = np.sum(R**2) / float(n - 2)
COV = S2 * np.linalg.inv(X.T @ X)
J = [1 / xx[1], -xx[0] / xx[1] ** 2]
J = [-1 / xx[1], xx[0] / xx[1] ** 2] # Jacobian [dr/d(xx[0]) , dr/d(xx[1])]
err = np.sqrt(J @ COV @ J)

# return x @y=0
Expand Down Expand Up @@ -346,7 +346,7 @@ def measure(
# Initial values
self._initial_k0 = [self._h_steer.strength.get(), self._v_steer.strength.get()]
self._initial_k1 = self._quad.strength.get()
self._quad_polarity = np.sign(self._initial_k1)
self._quad_polarity = np.sign(self._initial_k1) if self._initial_k1 != 0 else 1

self._ref_ios, fx, fy = self._init_responses(
self._cfg.tune_correction_name,
Expand Down
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