Calculation of least-squares fits
This is a step-by-step guide for calculating least-squares fits using the
standard fitting formula:
- Click on the Fit. tab
- After you have extracted a frequency by means of a Fourier calculation,
the frequency and amplitude are added to the frequency list. You may also
enter own frequency values.
- Activate the new frequency by selecting the check box at the beginning of
the frequency line.
- Select the type of data you want to use. By default "Original data" is
selected.
- If you want to use weighted data, set the appropriate weights. See
"Using weights" for more information on this topic.
- Press Calculate to improve amplitude and phase.
- Press Improve all to improve all parameters, including the value of
the frequency.
Period04 does also allow for more sophisticated least-squares fits:
- Improve special:
If you want to define a specific selection of parameters that should be
improved, then choose this option.
- Calculate amplitude/phase variations:
Use this if you suspect that the amplitude and/or phase of a parameter is
variable in different substrings.
- When the expert mode is active, it is possible to calculate least-squares
fits that include a periodic time shift. See "Using the periodic time shift mode" for more
information on this topic.