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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 Message: * HTML is OFF * Forum Code is ON Smilies [quote][i]Originally posted by DaveGohlke[/i] [br]Origin Ver. 8.0 SR6: Operating System: Win 7, 32bit. I am trying to fit a custom non-linear function for many files with varying x values and different numbers of peaks. (Each individual curve will be fit by the sum of two exponentials and several Gaussians.) Is it possible to programmatically set my Upper/Lower bounds for any variable? Currently, if there is one peak, and I ask for two Gaussians, the function might return one good Gaussian, and then one Gaussian centered outside of my range, with an unphysical width or height. I could hard-code my bounds in for each set of data if necessary, or manually filter the data in post-processing, but I want this to require as little human input as possible. My first work-around has been to add two new parameters in the initialization: maxx = max(x_data); minx = min(x_data); and then define my function as y = AVB*exp(-x/tVB) + ACB*exp(x/tCB) +y0 + A1*exp(-((x-xc1)/w1)^2); maxx; minx; if(w1 > (maxx-minx) || xc1 > maxx || xc1 < minx) { A1 = 0; xc1 = 0; w1 =1; } I'm a little concerned about convergence issues with this method (I think it might risk going in a loop), and would much prefer to set bounds as: 0 < w1 < max(x_data) - min(x_data) min(x_data) < xc1 < max(x_data) Can one adjust the bounds more variably in the parameter settings than "0(X, On)", "--(I, Off)"? Thanks, Dave PS: Sorry for overwhelming the forum with consecutive topics. I figured they were distinct enough to merit it. [/quote]   Check here to include your profile signature. Check here to subscribe to this topic.