Why not use median filtering with a small window ?
> Le 4 avr. 2016 à 07:57, t...@wescottdesign.com a écrit : > > As written (with or without the commenting out) that code won't produce phase > shifts. In technical terms it's a FIR filter that is symmetrical around zero > delay, and such filters do not introduce phase shifts. > > > >> On 2016-04-03 22:47, Claus Futtrup wrote: >> >> Hi Buk >> >> When data goes zig-zag like that, I'm sometimes successful with a Bartlett >> (triangular) smoothing window of only very few points (like 3 points). >> >> // function [out]=bartlett3p(indata) // for smoothing (when plotting) >> // out = indata; >> // if length(indata)>2 then >> // out(2:$-1) = 0.25*indata(1:$-2) + 0.5*indata(2:$-1) + >> 0.25*indata(3:$); >> // end // Bartlett Window = Triangular window >> endfunction >> >> Yes, it will affect your data, probably introduce phase shifts. >> >> Best regards, >> Claus >> >>> On 03-04-2016 21:09, scilab.20.browse...@xoxy.net wrote: >>> HI, >>> >>> The data I'm dealing with is experimentally produced; and thus contains >>> occasional, localised discontinuities (inflections), that I need to remove >>> before that data is suitable for is use in FEM modeling software, which >>> requires that it be strictly monotonic. The attachment shows the full curve >>> plus a close up of a couple of examples of the type of discontinuity I need >>> to deal with. >>> >>> I haven't yet decided whether to simply omit points (thus connect A to F & >>> G to J) or whether to retain the same number of points by interpolating new >>> points onto that line as shown in red. >>> >>> I've looked and played several of the smoothing, convolution and >>> interpolation routines that scilab provides, but (besides that I don't >>> understand the output some of them produce) they also seem to affect the >>> data more than I would like. Some seem to introduce a 'phase shift'; others >>> smooth out larger scale bumps in the curve that need to be retained; and >>> others generate many extra points which I don't think is helpful, the FEM >>> software is going to do its own interpolations anyway. >>> >>> >>> But the bit I'm asking about here is how to detect point A&F and G&J? >>> >>> Any thoughts or pointers as to a) the algorithm to use; b) how to implement >>> it in SciLab? >>> >>> Cheers, Buk. >>> >>> ____________________________________________________________ >>> Can't remember your password? Do you need a strong and secure password? >>> Use Password manager! It stores your passwords & protects your account. >>> Check it out at http://mysecurelogon.com/password-manager >>> >>> >>> _______________________________________________ >>> users mailing list >>> users@lists.scilab.org >>> http://lists.scilab.org/mailman/listinfo/users >> >> >> _______________________________________________ >> users mailing list >> users@lists.scilab.org >> http://lists.scilab.org/mailman/listinfo/users > > > > _______________________________________________ > users mailing list > users@lists.scilab.org > http://lists.scilab.org/mailman/listinfo/users
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