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ATLAS Offline Software
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Class that knows details of LogLikelihood approximation with a polynomial. More...
#include <T2TrackBSLLPoly.h>
Public Member Functions | |
| T2TrackBSLLPoly (double beam_size) | |
| void | update (double z0, double d0, double phi0, double d0_var, std::vector< double > &coeff) |
| Update polynomial coefficients with track data. | |
Private Attributes | |
| double | m_beam_size {} |
Class that knows details of LogLikelihood approximation with a polynomial.
Few particular things that this class handles:
The approximation of the LL function looks like (factorized):
LL = - (d_0 + B_x*sin(phi) - B_y*cos(phi) + t_x*z_0*sin(phi)
(ln(Sigma) + S_prime/Sigma - (S_prime/Sigma)**2/2)/2 var_b = beam_size**2 Sigma = var_d0 + var_b S_prime = omega_x*sin(phi)**2 + omega_y*cos(phi)**2
The variables here are (B_x, B_y, t_x, t_y, omega_x, omega_y), the rest are either track parameters or constants. beam_size is a constant which should be close to actual transverse beam size (typically 0.01 mm). In the expanded representation the polynomial terms have these possible combinations of powers of omega:
omega_x**2, omega_y**2, omega_x*omega_y, omega_x, omega_y, 1
with total of 6 variants and they don't depend on other variables. Four other variables can appear in the polynomial terms in these combinations:
Together with 6 omega combinations this gives (4+4*3/2+4+1)*6 = 90 monomials.
In addition to the 90 coefficients we also store other information in the monitored variables:
Definition at line 58 of file T2TrackBSLLPoly.h.
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inlineexplicit |
Definition at line 61 of file T2TrackBSLLPoly.h.
| void T2TrackBSLLPoly::update | ( | double | z0, |
| double | d0, | ||
| double | phi0, | ||
| double | d0_var, | ||
| std::vector< double > & | coeff ) |
Update polynomial coefficients with track data.
If vector is empty it is resized to have nbins() size, otherwise it has to be at least nbins() elements in size.
Definition at line 18 of file T2TrackBSLLPoly.cxx.
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private |
Definition at line 74 of file T2TrackBSLLPoly.h.