All Forums  Origin Forum for Programming  Forum for Origin C  Convolution with NLSF Problem

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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 phenning[/i] [br]Origin Ver. 8.0 (Demo) SR6 Operating System: Vista 64 SP2 I'm trying to analyze fluorescence lifetime data using the method here: http://wiki.originlab.com/~originla/howto/index.php?title=Tutorial:Fitting_With_Convolution This method works for the sample data provided by Origin, but I'm having problems with my data. NLSF only returns the first 100 or so points out of 512 datapoints in the dataset. Also, the time axis appears to be stretched in the fitting window. And, when I look at the output data, the time values are resampled (1,5,10... vs 1,2,3...). Also, when I plot the convoluted response against the original time axis, the fit is quite good, except that the tail end of the curve (80% of the data) is absent. However, the residuals are calculated for all time values in the original data. The tail end has a lot of significance to the recovered lifetimes/parameters for fluorescence lifetime data. I cropped the measured data to 512 points, then cropped the response function to 255 points, and finally cropped the response function to 233 datapoints. I've also tried this with simulated data using the convolution routine in Origin with my response function. In all cases, the result was the same as described above. I also tried to perform convolution without the FFT using the code below, but the NLSF only performed 1 iteration and it did not converge. The code produces the correct convolution with the response function when used as a function in OriginC, but does not seem to work in the NLSF wizard. for ( int i=0; i<Size; i++ ) { for( int j=i; j<Size; j++ ) { Temp = 0; Temp = vIRF[i] * Amp * exp(-(vTime[j]-Shift)/Tau); vConv[j] = vConv[j] + Temp; } } Any assistance is greatly appreciated. TIA [/quote]   Check here to include your profile signature. Check here to subscribe to this topic.