The fit folder


The fit folder contains two tabs:

The Main tab


In the upper part of the 'Main' folder buttons for loading or saving frequencies are situated. If the frequencies are imported from an external file, the file to be imported has to be formatted as shown below:
F1	8.24559279926746	 0.0368726838369623 	 0.191925673969421 
F2	8.86632000196593	 0.0315951342401606 	 0.201285085238147 
F3	(8.51414241709122	 0.00995255120153335 	 0.811823263345419 )
If the frequency parameters are enclosed by parentheses, the frequency will appear inactive in the frequency list.

Furthermore, some information regarding the current fit is given:
Selected frequencies The total number of active frequencies. A frequency is active (and will be included into calculations) when the respective check box is selected in the frequency list.
Zero point The zero point of the magnitudes/intensities resulting from the last calculated fit.
Residuals The residuals (chi) for the last calculated fit.

To the left of the import/export buttons and to the right of the information labels there is a toggle button, respectively.

A click on the left hand side toggle button detaches the 'Time string' tab from the main frame and places the 'Time string' panel left of the main frame, whereas a click on the right hand side toggle button causes the 'Fourier' tab to be detached and placed to the right of the main frame.
If your screen is wide enough this makes it possible to use Period04 without having to switch between the different tabs.

Settings for least-squares fit calculations

Fitting formula Displays the formula that is being used for least-squares fits.
Calculations based on This defines the type of data to be used for the next least-squares calculation.
Use weights Displays a string that indicates which weights are being used for the least-squares calculation. If no weights are used "none" will be displayed.
1 use the weights assigned to the substrings of attribute #1
2use the weights assigned to the substrings of attribute #2
3use the weights assigned to the substrings of attribute #3
4use the weights assigned to the substrings of attribute #4
puse point weight
duse deviation weight
Edit weight settings Opens the weight-selection dialog.

The frequency list


In the default mode the frequency list consists of text fields for frequency, amplitude and phase values and corresponding check boxes. If a check box is selected then the respective non-zero frequency will be included in the next least-squares calculation.

Input options for frequency fields:

It is possible to enter harmonics or frequency combinations into frequency fields as shown in the examples below:
=2f1 or =2*f1for the second harmonic of f1.
=f1+f3for a combination frequency which is defined as the sum of f1 and f3.
=2f1-3f4
or = 2*f1-3*f4
for a combination frequency which is defined as the difference of the second harmonic of f1 and the third harmonic of f4.
Please note: A reference to a frequency that is a combination itself, will be rejected by the program. If one of the frequencies listed in the combination is not active, the combination is not active either
If a frequency is a combination a little button showing the letter "C" will appear between the frequency check-box and the frequency text field. Click on this button to show the frequency value instead of the combination string and vice versa.
Note: Special behavior in Period04 version 1.0.2 and higher!
It now makes a difference for your compuations if you decide to display the frequency value or the combination string. If the combination string is shown the program acts just as it used to before, but if the frequency value is displayed Period04 will treat this frequency as a normal frequency.

Adding or subtracting the alias gap value:
In order to add the alias-gap value to the frequency value, enter a trailing '+'. Type '-' if you want to subtract the alias-gap value. Multiple '+' or '-' can also be used, e.g., '34.11+++' means 34.11 with three times the alias-gap value added. The default value for the alias-gap can be set by using the 'Set alias-gap dialog' in the Data Manager.


Extensions for the periodic time-shift mode

(available in expert mode only)

See also "Using the periodic time-shift mode" for an instruction to activate this option. If the periodic time shift (PTS) mode is active the frequency list is extended to contain input fields for the periodic time shift parameters.

Furthermore, two calculation buttons are available:
Search PTS start values Searches a good start value within a given range by means of Monte Carlo shots.
Improve PTS Starts a least-squares calculation to improve the time shift parameters. For this calculation all three parameters of the periodic time shift will be improved, while the parameters of all other frequencies will be kept fixed.
For the periodic time shift mode the buttons for showing the phase plot and the calculation of amplitude and/or phase variations will not be available.

The Goodness of Fit tab


In this tab the uncertainties of the parameters can be calculated. See "Estimation of uncertainties" for further details.

Info Launches the Period04 help system and shows a page with some information on how to use Period04 to estimate the uncertainties of fit parameters.
Calculate LS uncertainties Calculates either correlated or uncorrelated uncertainties for the fitted parameters via a least-squares calculation.
Monte Carlo Simulation Opens a dialog which allows for the calculation of uncertainties for the fitted parameters by means of a Monte Carlo simulation.
Print list Prints the content of the text field.
Export list Opens a file-selector to save the content of the text field to a file.

The Fourier folder