similar to: symbollic differentiation in R

Hi all, I've been working on improving R's optim() command, which does general purpose unconstrained optimization. Obviously, this is important for many statistics computations, such as maximum likelihood, method of moments, etc. I have focused my efforts of the BFGS method, mainly because it best matches my current projects. Here's a quick summary of what I've done: *

Hi I recently gave a presentation about Automatic Differentiation (AD) and R at the Eighth Euro AD Workshop in Oxford (17/07/09). The presentation was intended as a general introduction to R and the desire for a generic AD interface for R. During the presentation I emphasised the need and the high level of interest that the R community has in developing such an interface and that input from the

Hi, Could anyone tell me what is the command used in R to do 1. Differentiation 2. Newton Raphson method (Numerical Analysis in general...) Are there any packages separately for this? Thanks for your help! BR, Shubha [[alternative HTML version deleted]]

Hi all, I wrote a function called relist, which is an inverse to the existing unlist function: http://www.econ.upenn.edu/~clausen/computing/relist.R Some functions need many parameters, which are most easily represented in complex structures. Unfortunately, many mathematical functions in R, including optim, nlm, and grad can only operate on functions whose domain is a vector. R has a

Hi R People: Is there a package for automatic differentiation, please? thanks in advance, Erin -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: erinm.hodgess at gmail.com

In efforts to improve optimization tools for R, one of my interests has been getting automatic differentiation capabilities so that analytic rather than numerical derivatives can be used. They would be helpful in several other areas besides optimization, My timings show factors of the order of 1000s in time improvements by avoiding numerical derivatives in some cases. There has been some work in

Hello, I am trying to construct two matrices, F and V, composed of partial derivatives and then find the eigenvalues of F*Inverse(V). I have the following equations in ryacas notation: > library(Ryacas) > FIh <- Expr("betah*Sh*Iv") > FIv <- Expr("betav*Sv*Ih") > VIh <- Expr("(muh + gamma)*Ih") > VIv <- Expr("muv*Iv") I

Hi all, I am trying to implement the following matlab code with Ryacas : syms U x x0 C d1=diff(U/(1+exp(-(x-x0)/C)),x); pretty(d1) d2=diff(U/(1+exp(-(x-x0)/C)),x,2); pretty(d2) solx2 = solve(d2 == 0, x, 'Real', true) pretty(solx2) slope2=subs(d1,solx2) I have tried the following : library(Ryacas) x <- Sym("x");U <- Sym("U");x0 <-

Thanks for the response. Yes, I did study the vignette but did not understand it fully. Anyway, I have tried once again now. I am happy to say that I have got what I wanted. library(Ryacas) x <- Sym("x");U <- Sym("U");x0 <- Sym("x0");C <- Sym("C") my_func <- function(x,U,x0,C) { return (U/(1+exp(-(x-x0)/C)))} FirstDeriv <-

Have you studied the "Introduction to Ryacas" vignette that come with the package? Cheers, Bert Bert Gunter "The trouble with having an open mind is that people keep coming along and sticking things into it." -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip ) On Tue, Sep 19, 2017 at 2:37 AM, Vivek Sutradhara <viveksutra at gmail.com> wrote:

Hello, I am wondering if someone can help me. I have the following function that I derived using nls() SSlogis. I would like to find its derivative. I thought I had done this using deriv(), but for some reason this isn't working out for me. Here is the function: asym <- 84.951 xmid <- 66.90742 scal <- -6.3 x.seq <- seq(1, 153,, 153) nls.fn <- asym/((1+exp((xmid-x.seq)/scal)))

I think I am the first to use the $135 Avaya 4602 SIP phone, but I need some support from the community to fix one problem I have with it. The phone stops working after about 20-30mins if I have mailbox=context in Asterisk; when I do have mailbox=contect in asterisk the sip debug returns "481 extension does not exist." Anyone willing to help me figure out why? I.E. Is it an Asterisk

Hi all, As long as I've used R, add=TRUE hasn't worked in contexts like this: f <- function(x) x^2 X <- seq(0, 1, by=1/4) plot(f, col="blue") plot(X, f(X), col="red", type="l", add=TRUE) I attached a fix for version 2.6.2. Cheers, Andrew -------------- next part -------------- diff --git a/src/library/graphics/R/plot.R

Hi I am currently (for pedagogical purposes) writing a simple numerical analysis library in R. I have come unstuck when writing a simple Newton-Raphson implementation, that looks like this: f <- function(x) { 2*cos(x)^2 + 3*sin(x) + 0.5 } root <- newton(f, tol=0.0001, N=20, a=1) My issue is calculating the symbolic derivative of f() inside the newton() function. I cant seem to get R to

On Sun, 11 Dec 2005 clausen at econ.upenn.edu wrote: > Full_Name: Andrew Clausen > Version: 2.1.0 > OS: Debian GNU/Linux > Submission from: (NULL) (71.242.192.73) > > > Hi, > > When I type > > hist(x, freq=F) > > I get a density function, as I expect. However, if I type > > plot(hist(x, freq=F)) > > then I get the same output as if I had

Hi all, sample() has some well-documented undesirable behaviour. sample(1:6, 1) sample(2:6, 1) ... sample(5:6, 1) do what you expect, but sample(6:6, 1) sample(1:6, 1) do the same thing. This behaviour is documented: If 'x' has length 1, is numeric (in the sense of 'is.numeric') and 'x >= 1', sampling _via_ 'sample' takes place from

Hi all, Over the past 10 years, there has been some discussion and several patches concerning keystroke timing being revealed by the timing of openssh packet network transmission. The issue is that keystroke timing is correlated with the plaintext, and openssh users expect their communications to be kept entirely secret. Despite some excellent ideas and patches, such as Jason Coit's

This may be a question to R-development but I'm not sure. Symbolic differentiation is implemented in R (maybe not for extremely complex expressions), but it proves that it can be done. I know that in C++ it can be done (symbolic c++), do you think in R it can be programmed just using the R language without resorting to external sources? Does anyone know or can estimate the amount of resources

Hi I can't for the life of me work out why this is not working. When in the campon contect if you hit a DTMF key 2 you get moved to the exten => 2 defined in the mainmenu context not the exten => 2 defined in the campon context. What is wrong? The same happens if you hit key 1. [campon] exten => _*1XXX,1,Answer exten => _*1XXX,2,SetCallerID(${CALLERIDNUM}) exten =>

I was wondering if it was possible to get a Samba server that was acting as an AD member server to also be able to authenticate local users, or is stuck just serving AD users? -- Aaron Clausen mightymartianca at gmail.com