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42 lines
2.3 KiB
ReStructuredText
42 lines
2.3 KiB
ReStructuredText
Fitting the tail of a Matsubara Green's function
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#################################################
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API
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~~~~~
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The tail of a given ``gf<imfreq>/gf<block_index, gf<imfreq>> gw`` can be fitted using the two following functions:
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``void fit_tail(gf<imfreq> &gf, tail_view known_moments, int n_moments, size_t n_min, size_t n_max, bool replace_by_fit = false);``
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``void fit_tail(gf<block_index, gf<imfreq>> &block_gf, tail_view known_moments, int n_moments, size_t n_min, size_t n_max, bool replace_by_fit = false);``
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where
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+------------+----------------+----------------------------------------------------------------------+---------+
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| type | name | description | default |
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+============+================+======================================================================+=========+
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| gf<imfreq> | gf | Green's function to be fit (bosonic/fermionic) | no |
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+------------+----------------+----------------------------------------------------------------------+---------+
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| tail_view | known_moments | known part of the tail | no |
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+------------+----------------+----------------------------------------------------------------------+---------+
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| int | n_moments | number of moments in the final tail (including known ones) | no |
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+------------+----------------+----------------------------------------------------------------------+---------+
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| size_t | n_min | Matsubara index on mesh to start the fit | no |
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+------------+----------------+----------------------------------------------------------------------+---------+
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| size_t | n_max | final Matsubara index for fit (included) | no |
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+------------+----------------+----------------------------------------------------------------------+---------+
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| bool | replace_by_fit | if true, replace the gf data in the fitting range by the tail values | true |
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+------------+----------------+----------------------------------------------------------------------+---------+
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Example
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~~~~~~~~
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.. triqs_example:: ./fit_tail_0.cpp
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Implementation
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~~~~~~~~~~~~~~~
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The fitting problem is written as a linear system of equations, which is solved by SVD.
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