search for: raphson

Hi, Is there available package on the optimization function using Newton-Raphson method (iterative quadratic approximation)? I have been using the 'optim' function in R and found it really unstable (it depends heavily on the initial values and functional forms). If I have to code it by myself, can I get some advice on how to start (any good reference or sample code)? I...

Hello, Does anyone know whether the gls function in the nlme library uses the Newton-Raphson or EM algorithm to find the restricted log-likelihood or maximum log-likelihood estimates? Brendan Klick bklick@jhsph.edu [[alternative HTML version deleted]]

Hi, Does anyone know if there is a function to find the maximum likelihood estimates of glm using Newton Raphson metodology instead of using IWLS. Thanks Valeska Andreozzi -------------------------------------------------------- Department of Epidemiology and Quantitative Methods FIOCRUZ - National School of Public Health Tel: (55) 21 2598 2872 Rio de Janeiro - Brazil

Dear Mr.Zeileis & all. (1)     Thx for your reply. Yes, I am talk about the function zeroinfl() from the package "pscl". I want to use Newton Raphson to get parameter             estimation ZINB, so I try this: ----------------------------------------------------------------------------------------------------------------------------------         > zinb <- zeroinfl(y ~x1+x2+x3+x4+x5|x1+x2+x3+x4+x5, data = dat, link="logit",dist...

Dear all, I want to solve a score function by using Newton-Raphson algorithm. Is there such a fucntion in R? I know there's one called optim, but it seems only doing minimizing or maximizing. Thanks, Jimmy

...t included the previous postings because they came out very strangely on my mail reader. However, the question concerned the choice of minimizer for the zeroinfl() function, which apparently allows any of the current 6 methods of optim() for this purpose. The original poster wanted to use Newton-Raphson. Newton-Raphson (or just Newton for simplicity) is commonly thought to be the "best" way to approach optimization problems. I've had several people ask me why the optimx() package (see OptimizeR project on r-forge -- probably soon on CRAN, we're just tidying up) does not have...

Hi, Is there a routine available in R for the Newton-Raphson method for simulataneous equations in several unknowns? Thanks Robert -- Robert J. Chandran Department of Botany 3506 Miller Plant Sciences Building University of Georgia Athens, GA 30602 Phone: (706)-583-0943 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-h...

Dear all.. I have a respon variable y. Predictor variable are x1, x2, x3, x4, x5 (1) What is the syntax to get paramater estimation of ZINB Model by Newton Raphson (not BFGS) (2) What syntax to plot probability of observed & predicted of ZINB Thx. Regards Krist. [[alternative HTML version deleted]]

Hi I would like to use the newton raphson method to find the root if the equation x^3-0.165*x+0.0003993 without using any readliy available program in r but instead by writing my own code and loop. the problem is that i really cant understand how to write the loop so that it keeps using the last calcualted values. if anyone could help me...

can anyone tell me how can i control the method of estimation (i.e. scoring method or Newton raphson method) in glm and compute deviance function ? -- View this message in context: http://r.789695.n4.nabble.com/changing-method-of-estimation-in-GLM-tp3170836p3170836.html Sent from the R help mailing list archive at Nabble.com.

...give context for the problem, this is a psychometric issue where R is a vector denoting the percentage of students scoring correct on test item i in class j, c is the proportion correct on the test by student k, and q is the number of items on the test in total. I have programmed this using Newton-Raphson as follows: numer <- function(R,a,c,q){ result <- sum((1-(1-R)^a)^(1/a))-c*q result } denom <- function(R,a,c,q){ result <- sum(-((1 - (1 - R)^a)^(1/a) * (log((1 - (1 - R)^a)) * (1/a^2)) + (1 - (1 - R)^a)^((1/a) - 1) * ((1/a) * ((1...

Hi , I am trying to get some estimator based on lognormal distribution when we have left,interval, and right censored data. Since, there is now avalible pakage in R can help me in this, I had to write my own code using Newton Raphson method which requires first and second derivative of log likelihood but my problem after runing the code is the estimators were too high. with this email ,I provide simple example for estimation parameters for lognormal when we have only right censored data, and I tried to estimate the parameters u...

Hello all! I'd like to use a routine in R to find the zero of a function (like Newton-Raphson, Broyden, etc.) In the manual, I found a reference to Newton-Raphson method in the "qr" function, but I simply wonder how I could use it to implement such a method. Carlos -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http:/...

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]]

...(formula = y ~ pspline(x1, df = 2)) coef se(coef) se2 Chisq DF p pspline(x1, df = 2), line 0.0522 0.00867 0.00866 36.23 1.00 1.8e-09 pspline(x1, df = 2), nonl 3.27 1.04 7.5e-02 Iterations: 4 outer, 13 Newton-Raphson Theta= 0.91 Degrees of freedom for terms= 2 Likelihood ratio test=34.6 on 2.04 df, p=3.24e-08 2. survreg(formula = y ~ pspline(x1, df = 2)) coef se(coef) se2 Chisq DF p (Intercept) 2.8199 0.15980 0.09933 311.37 1.0 0....

Hi, I am trying to get the maximum likelihood estimator for lognormal distribution with censored data;when we have left, interval and right censord. I built my code in R, by writing the deriving of log likelihood function and using newton raphson method but my estimators were too high " overestimation", where the values exceed the 1000 in some runing of my code. is there any one can tell me where the error can be and help me in how I can get the estimators with right way?.  kind regards [[alternative HTML version deleted]]

Does this give correct results for special floats (0, infs)? We tried to improve (for single floats) x86 rcp in llvmpipe with newton-raphson, but unfortunately not being able to give correct results for these two cases (without even more additional code) meant it got all disabled in the end (you can still see that code in the driver) since the problems are at least as bad as those due to bad accuracy... Roland Am 23.02.2015 um 05:01 s...

Hi, I am relatively new to R and am trying to solve two simultaneous nonlinear equations in two variables numerically, and was wondering if anyone knew if any of the packages could do that. An alternative is writing my own code using Newton-Raphson; I did that but was not able to get good convergence. Any ideas please? Thanks Yogesh [[alternative HTML version deleted]]

Dear R-programmers, I am trying to program a Newton-Raphson in R (yes, i will try GSL, not right now), and it would be a real boon if R had tail call elimination, so that a recursive program has a guarantee not to fail due to stack overflows, given how slow loops in R are. I did look at the documentation, but could not find a reason for it. Regards, Mohit...

I'm trying to fit the Bass Diffusion Model using the nls function in R but I'm running into a strange problem. The model has either two or three parameters, depending on how it's parameterized, p (coefficient of innovation), q (coefficient of immitation), and sometimes m (maximum market share). Regardless of how I parameterize the model I get an error saying that the step factor has