search for: varadhan

Hello, I want to find the roots of an equation in two variables. I am aware of the uniroot function, which can do this for a function with a single variable (as I understand it...) but cannot find a function that does this for an equation with more than one variable. I am looking for something implementing similar to a Newton-Raphson algorithm. Thanks. -- Bill Shipley North American Editor for

...that it governs the rate at which the random process given by the stochastic matrix converges to its stationary distribution. Does anyone know of an algorithm to do this? Thanks for any help, Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvaradhan@jhmi.edu Webpage: <http://www.jhsph.edu/agingandhealth/People/Faculty_personal_pages/Varadhan. html&g...

...ny levels as there are values. I am unable to coerce this to "numeric" mode. Is there a way to do this so that I can then manipulate the numeric data frame? Thanks for any help. Best, Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvaradhan@jhmi.edu Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ----------------...

...<- seq(0,30,by=0.1) y0 <- c(0,0) parms <- c(k1=0.7, k2=0.5, k3=0.2, k4=0.8, T=10, delay=5) Is there a way to incorporate delay in odesolve? Any hints would be much appreciated. Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvaradhan@jhmi.edu Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ----------------...

...ly(B, 1, y=A[i,], function(x,y) g(y,x)) } g <- function(x,y){ theta <- atan((y[2]-x[2]) / (y[1] - x[1])) theta + 2*pi*(theta < 0) } Thanks for any suggestions. Best, Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvaradhan@jhmi.edu Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ----------------...

Dear R-users I would like to integrate something like \int_k^\infty (1 - F(x)) dx, where F(.) is a cumulative distribution function. As mentioned in the "integrate" help-page: integrate(dnorm,0,20000) ## fails on many systems. This does not happen for an adaptive Simpson or Lobatto quadrature (cf. Matlab). Even though I am hardly familiar with numerical integration the implementation

...ar(mfrow=c(2,2)) apply(X, 2, function(x)truehist(x)) In this example, I would like the x-labels of the histograms to be "X1", "X2", etc. Any help is appreciated. Best, Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvaradhan@jhmi.edu Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ----------------...

...version 2.6.1 on Windows XP. May I ask what the rationale behind this change is and also about the pros and cons of the two different ways of specifying (.)? Thank you very much. Best, Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvaradhan@jhmi.edu Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ----------------...

...r nlm()? I dowloaded the R2.8.1.tar.gz file and looked at all the .c and .f files, but couldn't find either nlm.c or nlm.f There is an nlm.r file, but that is not useful. Thanks for any help, Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvaradhan@jhmi.edu Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ----------------...

...{ p <- p + coef[i+1]* coef[j+1] * U[,i+j+1] } } I would appreciate any suggestions on how to perform this computation efficiently without the "for" loops? Thank you, Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvaradhan@jhmi.edu Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ----------------...

...as it was without the tireless efforts of Kate Mullen. The great thing about Kate is that she did so much without ever hogging the limelight. Thank you, Kate and thank you NIST! I cannot wait for UseR!2011! Best, Ravi. ____________________________________________________________________ Ravi Varadhan, Ph.D. Assistant Professor, Division of Geriatric Medicine and Gerontology School of Medicine Johns Hopkins University Ph. (410) 502-2619 email: rvaradhan at jhmi.edu

...s of V along the diagonal. This seems like a valid approach, but I still don't know how to specify the covariance structure to do weighted least squares. Any help is appreciated. Best, Ravi. ---------------------------------------------------------------------------- ------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: rvaradhan@jhmi.edu Webpage: http://www.jhsph.edu/agingandhealth/People/Faculty/Varadhan.html ----------------...

Hi, While using R CMD check I get the following Latex error message which occurs when creating PDF version of manual: LaTex error: File `inconsolata.sty' not found I am using Windows 7 (64-bit) and R 3.0.1. I have MikTex 2.9. I see that the incosolata.sty is present under \doc\fonts folder. How can I eliminate this problem? Thanks, Ravi [[alternative HTML version deleted]]

...be useful to extend this to also include colMin, colMax (of course, rowMin and rowMax, as well) in order to facilitate faster computations for large vectors (compared to using apply). Has this been considered before? Please forgive me if this has already been discussed before. Thanks, Ravi Ravi Varadhan, Ph.D. Assistant Professor The Center on Aging and Health Division of Geriatric Medicine & Gerontology Johns Hopkins University rvaradhan@jhmi.edu<mailto:rvaradhan@jhmi.edu> 410-502-2619 [[alternative HTML version deleted]]

...} fvals <- capture.output(ans <- optim(c(-1.2,1), fr)) Now, `fvals' contains character elements, but I would like to obtain the actual numerical values. How can I do this? Thanks very much for any suggestions. Best, Ravi. ------------------------------------------------------- Ravi Varadhan, Ph.D. Assistant Professor, Division of Geriatric Medicine and Gerontology School of Medicine Johns Hopkins University Ph. (410) 502-2619 email: rvaradhan@jhmi.edu<mailto:rvaradhan@jhmi.edu> [[alternative HTML version deleted]]

...hear about views on the future of GPGPU - i.e. is it here to stay or is it just a gimmick that will quietly disappear into the oblivion. Thanks very much. Best regards, Ravi. ---------------------------------------------------------------------------- ------------------------------ Ravi Varadhan, Ph.D. Assistant Professor, Center on Aging and Health, Johns Hopkins University School of Medicine (410)502-2619 rvaradhan@jhmi.edu http://www.jhsph.edu/agingandhealth/People/Faculty_personal_pages/Varadhan.h tml [[alternative HTML version deleted]]

Hey fellas: I would like to integrate the following function: integrand <- function (x,t) { exp(-2*t)*(2*t)^x/(10*factorial(x)) } with respect to the t variable, from 0 to 10. The variable x here works as a parameter: I would like to integrate the said function for each value of x in 0,1,..,44. I have tried Vectorize to no avail. Thanks in advance, jose romero

...correlation parameter, r, and I can then sample from the conditional [U | T=t] which is also a lognormal (parametrized by r). Does this sound right? Are there better/simpler ways to do this? Thanks very much for any hints. Best, Ravi. ------------------------------------------------------- Ravi Varadhan, Ph.D. Assistant Professor, Division of Geriatric Medicine and Gerontology School of Medicine Johns Hopkins University Ph. (410) 502-2619 email: rvaradhan@jhmi.edu<mailto:rvaradhan@jhmi.edu> [[alternative HTML version deleted]]

...hould have a length greater than 1, since "any" should give me a single logical value. Can any one tell me what is going on here? (I am using version 2.1.1 on Windows). Thanks very much, Ravi. -------------------------------------------------------------------------- Ravi Varadhan, Ph.D. Assistant Professor, The Center on Aging and Health Division of Geriatric Medicine and Gerontology Johns Hopkins University Ph: (410) 502-2619 Fax: (410) 614-9625 Email: <mailto:rvaradhan@jhmi.edu> rvaradhan@jhmi.edu -----------------------------------------------------------...

...ppropriately handle them in the post-processing of simulation results? I know that `try' can be used to capture errors, but I would like to capture and detect warnings. Any pointers would be appreciated. Thanks, Ravi. ____________________________________________________________________ Ravi Varadhan, Ph.D. Assistant Professor, Division of Geriatric Medicine and Gerontology School of Medicine Johns Hopkins University Ph. (410) 502-2619 email: rvaradhan at jhmi.edu