All Forums  Origin Forum  Origin Forum  NLFit algorithm

Note: Only the poster of this message, and the Moderator can edit the message.

Screensize: 640 x 480 800 x 600 1024 x 768 1280 x 1024 UserName: Password: Anti-Spam Code: Format Mode: Basic  Help  Prompt  Format: Font Andale Mono Arial Arial Black Book Antiqua Century Gothic Comic Sans MS Courier New Georgia Impact Lucida Console Script MT Bold Stencil Tahoma Times New Roman Trebuchet MS Verdana   Size 1 2 3 4 5 6   Color Black Red Yellow Pink Green Orange Purple Blue Beige Brown Teal Navy Maroon LimeGreen Forum: Origin Forum Subject: Message: * HTML is OFF * Forum Code is ON Smilies Hi everyone, I am using the NLFit tool in OriginPro and I would like to better understand the underlying mechanics of the Levenberg-Marquardt algorithm implementation, specifically regarding the Jacobian matrix. I have two questions concerning the calculation of derivatives: - Built-in Functions: How does Origin handle the Jacobian for its library of built-in functions? Does it use analytical Jacobians (exact formulas) or is it based on a numerical approximation approach? - User-Defined Functions (UDF): When a user creates a new fitting function, how is the Jacobian determined by the engine? I am interested to know if there is a default method (such as finite differences) and if there are options for the user to specify or influence how these derivatives are calculated to ensure better convergence.   Check here to subscribe to this topic.