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15.3 Quick Fit

Overview

The Quick Fit Gadget allows you to perform linear fitting and nonlinear curve fitting in a flexible and easy way, on data plotted in a graph. The tool creates a ROI (Region of Interest) object with which you can drag and choose a range of the curve to be fitted quickly. QuickFitMenu.png

With the Quick Fit Gadget you can:

  • Change the fitting data range by simply moving and resizing the ROI
  • Maintain a list of favorite fitting functions
  • Easily add to favorite functions list from a large selection of built-in fitting functions or user-defined functions
  • Display parameter values and/or fit statistics on top of ROI
  • Interactively perform multiple fit operations to multiple ranges of same dataset, or to multiple datasets in the graph layer
  • Append fit results to a worksheet, for consolidated results from multiple fitting operations
  • Launch the advanced NLFit tool using Gadget settings for data range, function, and parameter values
  • Find specific/new X/Y values using the fit curve
  • Save settings, including function, to a Theme file for repeat use.
To Use Quick Fit Gadget

To use Quick Fit gadget, select from menu Gadgets: Quick Fit when a graph window is active.

Settings tab

Fit Mode Select either Polynomial Fit or Nonlinear Curve Fit with this drop-down list. After the selection, the corresponding functions will be listed in the Function drop-down list.
Function You can choose a function with which to perform the fitting. Note that you can add more functions to this list by selecting the <more> option to open the Edit Quick Fit Function List dialog.


Edit Function List

EditFunctionList QuickFit.png
In this dialog, you can add or remove functions which are listed in the Quick Fit Function List. You can also reorder the function list by dragging-and-dropping or using the right-click menu to move up or move down.
Apparent Fit This check box is only available when the Fit Mode is set to Polynomial Fit.

Specify whether to use the apparent values for fitting, according to the current axis scales. For example, select this box to fit exponentially decaying data with a straight line fit when data are plotted on a log scale.

When this check box is selected and the data has error values associated with it, Origin uses the larger of the positive/negative errors as weight.

Apparent fitting is only useful when the fitting is started from a graph with non-linear axes (Log10, for example). If you check this option, the fitter will first transform raw data into a new data space according to the axis types, and then perform the fitting on the transformed data. As you can see, apparent fitting is equivalent to transforming the raw data in worksheet and then applying a direct fitting.


ROI Box tab

Specify the ROI (Region of Interest) settings. The fitting will be performed within the ROI range.

X Scale From Specify the starting ROI X value.
X Scale To Specify the ending ROI X value.
Fix(Prevent moving by ROI) Specify whether to fix the X scale of the ROI box. Once this check box is checked, moving and resizing the ROI box are forbidden.
Show ToolName Specify whether to show this tool's name on the graph.
Show Rectangle after Fit Specify whether to show the rectangle over the graph after fitting.
Significant Digits Specify the significant digits. The default System significant digits can be set in Option dialog. See also: system digits.
Show on Center-Top of ROI Box Specify the values that will be shown on the center-top of ROI box.
Parameter List All parameters of the fitting function will be listed in the tree node and you can select them as you need to show them on the center-top of ROI.
Fill Color Specify the ROI rectangle color.
Fit Curve Color Specify fitted curve color.

Label Box tab

This tab controls the result text box content that is pasted on the graph.

Add Label Box to Graph Specify if you want to paste the result text box to the source graph.
Significant Digits Specify the significant digits. The option System mean using the settings set in Option dialog. See also: system digits.
Function Specify whether to show the fitting function name.
Input Specify whether to show the name of the input dataset in the Label Box. Options include:
  • None
    Do not show the name of the input dataset.
  • [Book]Sheet!Short Name
    Show the name of the input dataset as [Book]Sheet!Short Name.
  • [Book]Sheet!Long Name
    Show the name of the input dataset as [Book]Sheet!Long Name.
  • Long Name only
    Only show the long name of the input dataset.
  • Plot Legend
    Show as the Legend of the plot.
Range Specify whether to show the range of the input dataset in the Label Box. Options include:
  • None
    Do not show the range.
  • Indices
    Use the indices to identify the range of the input dataset.
  • X Values
    Use the X values to identify the range of the input dataset.
Output Specify whether to show the name of the fitted dataset in the Label Box.
  • None
    Do not show the name of the fitted dataset.
  • [Book]Sheet!Short Name
    Show the name of the fitted dataset as [Book]Sheet!Short Name.
  • [Book]Sheet!Long Name
    Show the name of the fitted dataset as [Book]Sheet!Long Name.
  • Long Name only
    Only show the long name of the fitted dataset.
  • Plot Legend
    Show as the Legend of the plot.
Add Legend Symbols Specify whether to add legend symbols to the Label Box.
Equation Show the fitting function equation, with parameter name or substitute parameter names by fitted values.
Parameter Table Specify fitted parameters to be output.
  • None
    Do not output the fitted parameters
  • All Parameters
    Output all of the parameters
  • Use ROI Box Tab Settings
    Output the parameters that selected under ROI Box tab.
Show Error in Parameter Table Specify whether to show the parameters' standard errors.
Reduced Chi-Sqr Specify whether to show the Reduced Chi-Square value.
R-Square Specify whether to show the R-Square value.
Pearson's r Specify whether to show Pearson's r (correlation coefficient) value.

Report tab

Besides the result text box pasted on the source graph, you can also output the fitted report to other destinations. Detailed settings can be specified in this tab.

Output To Specify output report destination.
Significant Digits Specify the significant digits. The default option System means using the significant digits setting in the Options dialog.
Function Specify whether to output the fitting function name.
Input Specify whether to show the name of the input dataset in the report. Options include:
  • None
    Do not show the name of the input dataset.
  • [Book]Sheet!Short Name
    Show the name of the input dataset as [Book]Sheet!Short Name.
  • [Book]Sheet!Long Name
    Show the name of the input dataset as [Book]Sheet!Long Name.
  • Long Name only
    Show the long name of the input dataset.
  • Plot Legend
    Show as the Legend does.
Add Range Specify whether to show the range of the input dataset in the report. Options include:
  • None
    Do not show the range.
  • Indices
    Use the indices to show the range of the input dataset.
  • X Values
    Use the X values to show the range of the input dataset.
Output Specify whether to show the name of the fitted dataset in the report.
  • None
    Do not show the name of the fitted dataset.
  • [Book]Sheet!Short Name
    Show the name of the fitted dataset as [Book]Sheet!Short Name.
  • [Book]Sheet!Long Name
    Show the name of the fitted dataset as [Book]Sheet!Long Name.
  • Long Name only
    Show the long name of the fitted dataset.
  • Plot Legend
    Show as in the Legend of the plot.
Equation Specify whether to output the fitting function equation.
  • None
    Do not output the fitting function equation
  • Equation with Names
    Output the equation with parameter names
  • Equation with Values
    Output the equation with the fitted values of parameters
Parameter Table Specify whether to output the parameter table.
  • None
    Do not output the fitted parameter table
  • All Parameters
    Output all of the parameters
  • Use ROI Box Tab Settings
    Output the parameters that selected in the ROI Box tab.
Show Error in Parameter Table Specify whether to output the parameters' standard errors.
Reduced Chi-Sqr Specify whether to output the Reduced Chi-Square value.
R-Square Specify whether to output the R-Square value.
Pearson's r Specify whether to output Pearson's r (correlation coefficient) value.

Fit Curve tab

Specify the fitted curve settings.

X Data Type Specify how to generate the X values of the fitted curve.
  • Same X as Source Data
    The X values of the fitted curve are the same as the input X values.
  • Use Source Graph Scale Type
    The X values of the fitted curve are plotted on the source data scale type.
  • Uniform Linear X
    The X values of the fitted curve are plotted on an equally-spaced linear scale.
Number of Points Specify the number of fitted curve points.
Range This control is available only when X Data Type is either Uniform Linear or Log. It specifies the range of the X values of the fitted curve. Select one of the following options:
  • Use Input Data Range + Margin
    Use the X range of the input data and range margin specified in the Range Margin (%) text box below.
  • Span to Full Axis Range
    Span the X values to the full axis range.
  • Custom
    Enter the minimum X value and maximum X value in the Min and Max edit boxes below.
Range Margin(%) This control is available only when Use Input Data Range + Margin is selected for Range. It specifies the range margin into which the fitted curves extend.
Output Fit Curve To Specify the fitted curve data destination.

Settings on the ROI

After you select the appropriate function for quick fitting, a yellow (default option) rectangle (ROI) will be added to the graph as below.

QuickFit ROI.png

There are two small buttons at the top-right of the ROI. Click ROI close.png button to close the ROI and click ROI menu.png to expand the following menu.

ROI menu2.png

New Output Output the fitting results of current curve. You can specify what to output in Label tab and Report tab.
New Output for All Curves(N) Output the fitting results of all curves in current layer.
New Output for All Layers(L) Output the fitting results of all curves in all layers of current graph.
Update Last Output Update the Label Box and the Report output.
Go to Report Worksheet Active the report worksheet if it was created.
Change Data Change fitting data/plot.
Change Function Change fitting function.
Expand to Full Plot Range Expand the ROI to full plot range.
Fix ROI Position Fix the ROI Position. This item is same as the Fix(Prevent moving by ROI) check box in the ROI Box tab.
Switch to NLFit/Polynomial Fit/Linear Fit... Open the NLFit/Polynomial Fit/Linear Fit dialog. The ROI range and specified fitting function will be inherited to the NLFit/Polynomial Fit/Linear Fit dialog.
Find X/Y Open the Quick Fit Find X/Y dialog, which can be used to calculate the X/Y values for given Y/X.
Save Theme Save the quick fit settings as theme.
Load Theme Load quick fit settings.
Preferences Open the Quick Fit Preferences dialog and reset the quick fit settings.

Note that, you are not allowed to reset fitting function in this dialog. To change fitting function, you can go to the above Change Function menu. Once the fitting function is set to linear or polynomial, the Settings tab with Apparent Fit check box will be available in this dialog.

 

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