• NAME
• VERSION
• SYNOPSIS
• DESCRIPTION
• ATTRIBUTES
• METHODS
• SERIALIZATION AND DESERIALIZATION
• CONFIGURATION AND ENVIRONMENT
• DEPENDENCIES
• BUGS AND LIMITATIONS
• AUTHOR
• LICENCE AND COPYRIGHT

NAME

Demeter::LogRatio - Log-ratio/phase-difference analysis

VERSION

This documentation refers to Demeter version 0.9.26.

SYNOPSIS

  #!/usr/bin/perl
  use Demeter qw(:ui=screen :plotwith=gnuplot);

  my $standard = Demeter::Data->new(file=>'../../data/fe.060.xmu', name => 'Fe 60K');
  my $data     = Demeter::Data->new(file=>'../../data/fe.300.xmu', name => 'Fe 60K');
  my $lrpd     = Demeter::LogRatio->new(standard=>$standard, data=>$data, qmax=>11);
  $lrpd->fit;
  print $lrpd->report;
  $lrpd->plot_odd;
  $lrpd->data->pause;

DESCRIPTION

Perform a log-ratio/phase difference analysis of two spectra in the manner of “Application of the Ratio Method of EXAFS Analysis to Disordered Systems”, G. Bunker, Nucl. Inst. Meth., 207, (1983) p. 437-444.

ATTRIBUTES

data

The unknown Data object.

standard

The standard Data object.

cumulants

After the fit, this gets filled with a reference to an array of the cumulants in order from zeroth to fourth.

errorbars

After the fit, this gets filled with a reference to an array of the uncertainties on the cumulants in order from zeroth to fourth.

qmin [3]

The lower end in q of the fitting range.

qmax [12]

The upper end in q of the fitting range.

twopi [0]

Manually add an integer number of two-pi jumps to the phase-difference spectrum.

METHODS

fit

Perform the log-ratio and phase-difference fits.

  $lr -> fit;

Note that the forward and backward Fourier transform parameters of the data are set to those of the standard before the fit is performed. They are not restored, thus performing a fit might modify the attributes of the unknown data.

report

Return a text string reporting on the cumulant values.

  print $lr->report;

plot_even

Make a plot of the log-ratio along with its polynomial fit.

  $lr->plot_even;

plot_odd

Make a plot of the phase-difference along with its polynomial fit.

  $lr->plot_odd;

SERIALIZATION AND DESERIALIZATION

Good question ...

CONFIGURATION AND ENVIRONMENT

See Demeter::Config for a description of the configuration system. See the lcf configuration group for the relevant parameters.

DEPENDENCIES

Demeter's dependencies are in the Build.PL file.

BUGS AND LIMITATIONS

• Better error checking

Please report problems to the Ifeffit Mailing List (http://cars9.uchicago.edu/mailman/listinfo/ifeffit/)

Patches are welcome.

AUTHOR

Bruce Ravel, http://bruceravel.github.io/home

http://bruceravel.github.io/demeter/

LICENCE AND COPYRIGHT

Copyright (c) 2006-2018 Bruce Ravel (http://bruceravel.github.io/home). All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlgpl.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.