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25 lines
864 B
Python
25 lines
864 B
Python
#!/usr/bin/env python
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# coding: utf-8
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import scipy.optimize
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from autograd import jacobian
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from .pyerrors import derived_observable, pseudo_Obs
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def find_root(d, func, guess=1.0, **kwargs):
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"""Finds the root of the function func(x, d) where d is an Obs.
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Parameters
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-----------------
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d -- Obs passed to the function.
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func -- Function to be minimized. Any numpy functions have to use the autograd.numpy wrapper
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guess -- Initial guess for the minimization.
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"""
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root = scipy.optimize.fsolve(func, guess, d.value)
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# Error propagation as detailed in arXiv:1809.01289
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dx = jacobian(func)(root[0], d.value)
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da = jacobian(lambda u, v: func(v, u))(d.value, root[0])
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deriv = - da / dx
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return derived_observable(lambda x, **kwargs: x[0], [pseudo_Obs(root, 0.0, d.names[0], d.shape[d.names[0]]), d], man_grad=[0, deriv])
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