search for: lorentzian

..., thanks to all who helped me with my question about rescaling axes on the fly. Using unlist() and range() to set the axis ranges in advance worked well. I've since plotted about 300 datasets with relative ease. Now I'm trying to fit a lossy oscillator resonance to (the square root of) a lorentzian (testframe$y is oscillator amplitude, testframe$x is drive frequency): lorentz <- nls( y ~ a0 / (Q*sqrt((1-(x/f0)^2)^2 + ((x/f0) * 1/Q)^2)), data = testframe, start = list (a0=1.4, f0=84321.6, Q=600000)) and am running into lots of convergence trouble (singular de...

> But such thinking is invalid for nonlinear mechanisms. > [...] I may fit it with a set of 5 Lorentzians > or, for more accuracy, with 10 Lorentzians. Doing so, the > resulting 10 Lorentzians _wont_ include the less accurate > 5 Lorentzians as a subset! Since 'bitrate peeling' is already supported, I believe it would be possible to transmit the 'peeled' stream and another st...

Dear all, I am using the nlsLM function to fit a Lorentzian function to my experimental data. The LM algorithm should allow to specify limits, but the upper limit appears not to work as expected in my code. The parameter 'w', which is peak width at half maximuim always hits the upper limit if the limit is specified. I would expect the value to be in...

Hi, I have a newbie question, and a not-so-newbie one. I've just found out about Ogg, and I haven't been able to find a clear answer in the many webpages this proyect has (btw, why not create just one site instead of vorbis.com, ogg-vorbis.com...). The question is, does Ogg use perceptual coding, like mp3 does? And if so, would it be possible to build an encoder in such a way as to

...tunately not (yet) implemented in R is described in http://www.graphpad.com/articles/RobustNonlinearRegression_files/frame.htm <http://www.graphpad.com/articles/RobustNonlinearRegression_files/frame.htm> in short: instead of using the premise that the residuals are gaussian they propose a Lorentzian distribution, in stead of minimizing the squared residus SUM (Y-Yhat)^2, the objective function is now SUM log(1+(Y-Yhat)^2/ RobustSD) where RobustSD is the 68th percentile of the absolute value of the residues my question is: is there a smart and elegant way to change to objective function fro...

...ke to generate random numbers from a Voigt distribution, hopefully in a way as simple as getting random numbers from a normal distribution with 'rnorm'. Is there any package to do this? Speed is an issue in this application. Or, as the Voigt distribution is a convolution of a Gaussian and a Lorentzian, can I simply combine random numbers from rnorm and rcauchy in some way (I'm not sure about the maths of this)? Best wishes, David. <DIV><FONT size="1" color="gray">This e-mail and any attachments may contain confidential, copyright and or privileged material, a...

...ke to generate random numbers from a Voigt distribution, hopefully in a way as simple as getting random numbers from a normal distribution with 'rnorm'. Is there any package to do this? Speed is an issue in this application. Or, as the Voigt distribution is a convolution of a Gaussian and a Lorentzian, can I simply combine random numbers from rnorm and rcauchy in some way (I'm not sure about the maths of this)? Best wishes, David. <DIV><FONT size="1" color="gray">This e-mail and any attachments may contain confidential, copyright and or privileged material, a...