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Is the matrix exponential available in some package? The cannonical reference is "Nineteen dubious ways to take the exponential of a matrix". (Love that title) Terry T.

Hi all, I am going to sample two variables from two exponential distributions, but I want to specify a covariance structure between these two variables. Is there any way to do it in R? Or is there a "Multivariate Exponential" thing corresponding to the multivariate normal? Thanks in advance. Sincerely, Yanwei Zhang Department of Actuarial Research...

Any one know is there any package or function to generate bivariate exponential distribution? I gusee there should be three parameters, two rate parameters and one correlation parameter. I just did not find any function available on R. Any suggestion is appreciated. -- View this message in context: http://r.789695.n4.nabble.com/How-to-generate-bivariate-exponential-distri...

Dear R-help, Here's a simple example of nonlinear curve fitting where nls seems to get the answer wrong on a very simple exponential fit (my R version 2.7.2). Look at this code below for a very basic curve fit using nls to fit to (a) a logarithmic and (b) an exponential curve. I did the fits using self-start functions and I compared the results with a more simple fit using a straight lm() command. The logarithmic fit works 1...

...as follows: ets(x,model="AZZ",opt.crit="mse") As to my observation about 5-10 of them have been identified by ets to have a trend and an alpha, beta values have been thrown up - which have been same in all these cases. When I read up online it came up as a Brown's double exponential smoothing as opposed to Holt's exponential smoothing (where alpha and beta differ). I am guessing this is happening as AIC/AICc/BIC select a model based on accuracy as well as a weight on number of parameters (1 in case of brown's, 2 in case of holt's). Now if I want to see results of...

Hi, I am trying to figure out the observed acceptance rate and M, using generalised rejection sampling to generate a sample from the posterior distribution for p. I have been told my code doesn't work because I need to "take the log of the expression for M, evaluate it and then exponentiate the result." This is because R is unable to calculate high powers such as 545.501. As you can see in my code I have tried to taking the log of M and then the exponential of the result, but I clearly must be doing something wrong. I keep getting the error message: Error in if (U <= r...

We need help.... We are doing a project for a statistical class in and we are looking at world record times in different running events over time. We are trying to fit the data with a negative exponential but we just cant seem to get a function that works properly. we have on our x-axis the date and on the y-axis the time(in seconds). So as you can imagine, the times have decreased and appear to be approaching a limit. Any ideas for a nls function that would work for us would be greatly appreciat...

Hi all, I have a dataset which consists of 2 columns. I'd like to plot them on a x-y scatter plot and fit an exponential trendline. I'd like R to determine the equation for the trendline and display it on the graph. Since I am new to R (and statistics), any advice on how to achieve this will be greatly appreciated. Many thanks, Chris -- View this message in context: http://n4.nabble.com/R-exponential-regress...

I am learning glm function, but how do you fit data using exponential distribution with glm? In the help file, under "Family Objects for Models", no ready made option seems available for the distribution as well as for other distributions satisfying GLM requirements not listed there.

Hi all, I am attempting to fit, and test the goodness of fit of, a mixed exponential distribution to my dataset which consists of 15minute rainfall intensity data. FYI, the dataset spanning approx.2 years and 7 rainfall stations consists of some three hundred thousand 15min data records, of which some 30 thousand are non-zero rainfall amounts. Could anyone please tell me how i c...

Hi Guys, Im trying to find the exponential of a matrix. Can someone please help me do this? Thanks a lot _________________________________________________________________ View photos of singles in your area Click Here =1&lage=18&uage=55&cl=14&sl=0&dist=50&po=1&do=2&trackingid=1046138&a...

Dear R-users! I would like to fit exponential, Weibull and log-logistic via glm() like functions. Does anyone know a way to do this? Bellow is a bit longer description of my problem. Hm, could family() be adjusted/improved/added to allow for these distributions? SAS procedure GENMOD alows to specify deviance and variance functions to help...

Hello! I have a problem which I have tried to solve for several days now.. I have plottet a lineplot.CI in the library "sciplot", and I am trying to plot it with a logaritmic y-axis (with exponential base). The problem is that; when I type "log "y"", the axis transforms into the logaritmic of base 10. I wonder if someeone could tell me how to specify that I would like to use the exponential logaritmic y-axis. I have tried a lot (but obviously not all, I guess this proble...

Hi, I'm trying to use ad.test or ad2.test to test whether a given data set is exponential. I see that one of the function inputs is "distn", but I try "exponential" and 5 other variants, but I still get the error message: ad.test(test2, distn="exponential", fit=list(estimate = 0.167685), H=NA, sim=100) Error in ad.test(test2, distn = "exponential&q...

Hello! I must estimate the parameters of a exponential power density. There is the normalp package, but this works only for a shape parameter bigger than 1. But what should i do if the shape parameter is less than 1? (Sorry for my english) Thank you very much for help! -- View this message in context: http://www.nabble.com/Parameters-of-exponential-...

Hi there, I'm quite new to R (and statistics), and I like it (both)! But I'm a bit lost in all these packages, so could someone please give me a hint whether there exists a package for fitting exponential curves (of the type t --> \sum_i a_i \exp( - b_i t)) on a noisy signal? In fact monoexponential decay + polynomial growth is what I'd like to try. Thanks in advance, Mirko. -- Dr. M. Luedde <Mirko.Luedde at CellControl.De> CellControl Biomedical Laboratories AG Am Klopferspitz...

There are a couple of points to keep in mind when doing a log-transform of an exponential model, such as -- y = a*exp(b*x) 1. The implicit statistical model is multiplicative in the error. The implied statistical model of the log transform is -- log(y) = log(a) + b*x + u which implies -- y = a*exp(b*x)*exp(u) A linear regression i...

Dear Mr. for writing program about Gibbs sampling, i have a question. if i want to generate data from Exponential distribution but range of X is restricted, how can i do? regards, A.Rashidi   [[alternative HTML version deleted]]

In glm, is there a way to specify the family to be exponential, or Gamma but with alpha=1? This is required by Dobson Exercise 4.3d, page 48. But without specifying alpha=1, the asnwer is the same as in the book. If reply to the list, please cc me a copy. Thanks. -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help maili...

could someone help me to write a fonction doing an exponential smoothing in case of a multivariate time serie? I tried ewma <- function (x, lambda = 1, init = 0) { if (is.ts(x)) filter(lambda*x, filter=1-lambda, method="recursive", init=init) else stop(message="first argument should be a time serie") } but I can...