File Exchange > Data Analysis >    Fitting Function Library

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Fitting Fu...ry.opx
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Let Origin user search, find and add fitting functions to Origin.

Screen Shot and Video:


The purpose of this app is to allow Origin user search, find and add new fitting functions to Origin. Simply select the function and click a button to download the FDF file and add the function to Origin, then find and use it when perform fitting.

Basic Usage

Note: Please keep your computer network running smoothly, or this app won’t run properly.

  1. Open Fitting Function Library from App Gallery.

This App needs to download the necessary image files of sample curve and formula from Origin server when you open it for the first time. So if you find this app is initializing, expect a bit of a delay.

  1. Click to select the function as desired from the table. The sample curve, model expression, keywords and note will be displayed in the lower panel in the meantime.
  2. Move the mouse over sample curve or model expression to see a large image.
  3. Same as usual, enter Ctrl or Shift then click to select multiple functions.
  4. Click Download button to add the selected functions to Origin. Note that the FDF files and related DLL files will be downloaded from Origin server and save in <User File Folder\fitfunc>.

Options and Hints

  1. Search box: enter function name, category or keyword to narrow down the candidate functions.
  2. Green Tick: the green tick shows if this function has been added to Origin or not.
  3. Category filter: select one of the categories from the drop-down to filter functions.
  4. Request a Function button: click to open a webpage and fill the form to ask for a new fitting function. Please provide the detailed info for the requested function in the form, includes function name, parameters (better with the bounds values for parameters if they have), formula, background and reference.

  5. Add to User-Defined Category checkbox: the selected function will be also added to User-Defined category other than its own categories if this checkbox is checked.
  6. Messages Log hint: this app will print out the message about the added functions and their categories in Messages Log window after clicking Add to Origin button.


  1. This app will update the function list automatically if Origin provides some new functions even after installation.
  2. If the functions that have been added to Origin are updated, this app will allow user to select whether to update the source of functions from the server to the local workspace or not.

Function List

This app provides more than twenty fitting functions, including convolution of a Gaussian function and a two-phase exponential decay function, modified diode or solar cell equation with series and shunt resistance using Lambert W function, convolution of a Doniach Sunjic function and a Gaussian function, cross-WLF viscosity model, stretched exponential function, Hikami-Larkin-Nagaoka equation, modified Arrhenius equation and so on.

All fitting functions that this app contains are listed here.


2.09 Fix bug of updating DLL
2.05 Cosmetic changes
1.9 Cosmetic changes
1.8 Support to check needed Python packages before loading fdf file
1.6 Support to detect min version for selected functions
1.5 Allow to open from NLFit dialog; change to download files from new server
1.2 New selected row style, show hints for a part of functions.
1.11 Add a new button to let user share a fitting function and fix bugs.

Reviews and Comments:


01/17/2022myan1113It's really helpful



You can click "Request a Function" button to ask for these two functions.

OriginLab Technical Support Team

04/10/2019B20170149为什么没有Split-Pearson VII或者Split-PV函数呢,这些在XRD峰形分析中应该是非常常用的函数

01/22/2019zhqhermIt's really helpful