similar to: symbolic manipulations

Full_Name: Lyle W. Konigsberg Version: 1.5.1 OS: Windows Submission from: (NULL) (160.36.64.99) I apparently found an error in how "deriv" puts a derivative to the screen (though the internal representation is correct). Here's what I was doing for a class example: > lnlk<-expression(15*log(p)+11*log(1-p)) > p<-15/26 > D(D(lnlk,"p"),"p") -15 *

Hi, I have a dataframe, hilodata, which looks like this: > hilodata sym date maxprice minprice ntick 1 ABK 19910711 11.1867461 0.0000000 108 2 ABK 19910712 11.5298979 11.1867461 111 3 ABK 19910715 11.7357889 11.4612675 52 4 ABK 19910716 11.5298979 11.3240068 51 5

Hi, I have a few questions about how to handle large data sets in R. What is the size of the largest matrix that R can comfortably deal with? Is this size limit imposed by R's software, or is it a question of the machine that one runs on? How does one go about choosing reasonable values of vsize and nsize? I have a data set with about 1,000,000 rows, and 30

Hi All, I have a dataframe, divs, that looks like this: > divs date ticker dividend 263 20010322 ADBE 0.025 264 20010628 ADBE 0.025 265 20010927 ADBE 0.025 4308 20010212 ED 0.550 4309 20010514 ED 0.410 5416 20010330 GE 0.137 5417 20010629 GE 0.137 5418 20010928

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 <-

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:

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 <-

Dear R People: When the D function is used for a symbolic derivative, an expression is returned, which is fine. How do you change that expression to a function, please? I've been experimenting with substitute and deparse, but no success yet. This is R 1.8.0 for Windows. thanks in advance for the help! Sincerely, Erin Hodgess mailto: hodgess at gator.uhd.edu

Dear everyone, the following is obviously used to compute the nth derivative, which seems to work (deriv(sqrt(1 - x^2),x,n)) However, before using this, I wanted to make sure it does what I think it does but can't figure it out when reading the ?deriv info or any other documentation on deriv for that matter: deriv(expr, namevec, function.arg = NULL, tag = ".expr", hessian = FALSE,

Dear list, Hi, I am trying to get the second derivative of a logistic formula, in R summary the model is given as : ### >$nls >Nonlinear regression model >model: data ~ logistic(time, A, mu, lambda, addpar) >data: parent.frame() > A mu lambda >0.53243 0.03741 6.94296 ### but I know the formula used is #

Dear All, I tried following for getting derivative of a polynomial in R i<- -10:10 x<-i*i*i+3*i*i+2 fun_spline<-splinefun(i,x) plot(x,type="l") lines(x,fx_spline(x, deriv=1), col='green') lines(x,fx_spline(x, deriv=2), col='green') Now when I plot 3*i*i + 6*i and 6*i + 6 the plot was not same for first deivative. where as the 2nd derivative was same Is this a

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)))

Hello, I have been trying to take the derivative of a quadratic B-spline obtained by using the COBS library. What I would like to do is similar to what one can do by using fit<-smooth.spline(cdf) xx<-seq(-10,10,.1) predict(fit, xx, deriv = 1) The goal is to fit the spline to data that is approximating a cumulative distribution function (e.g. in my example, cdf is a 2-column matrix with x

Hi, I have what I think is an easy question. I have a data frame, called stockdata, of stock prices that looks like this: date ticker close 1 01/02/1998 GE 24.667 2 01/05/1998 GE 25.104 3 01/06/1998 GE 24.771 4 01/07/1998 GE 24.979 5 01/08/1998 GE 24.750 6 01/02/1998 HIT 71.125 7 01/05/1998 HIT 72.313

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

Hello, I am trying to find a hessian matrix that involves log(gamma(1/p)) second derivative, p being one of the parameters of the function. I am using a function "deriv" with the hessian=TRUE option, but psigamma is not on the list of derivative functions. I know that it is possible to use 'psigamma(p,deriv)', but it doesn't work with 1/p. Does anybody can help with this?

Readers, A data set comprises A B C 10 6 .2 20 7 .4 30 8 .16 40 9 .0256 My requirement is to obtain the derivative for values of A with respect to B, create a function in R and plot this derivative against another variable (e.g. values in column C). Have searched the mailing list and found reference to a function 'D', but the help accessed via '?D' and '?deriv' does not

Hi, Suppose I have an arbitrary function: arbfun<-function(x) {...} Is there a robust implementation of a numerical derivative routine in R which I can use to take it's derivative ? Something a bit more than simple division by delta of the difference of evaluating the function at x and x+delta... Perhaps there is a way to do this using D or deriv but I could not figure it out.

Dear helpers, In an attempt to use a loop to generate graphs in a for loop in run into a problem. The plan is to fill each page with eight graphs (mfrow = c(4,2)) in to two columns. Only the buttom graphs ( meaning every fourth graph) have tick labels on the x axis to preserve space. I used an if .... Else statement to achieve that. The problem is that the first eight graphs are skipped

The derivative table resides in the function D. In S+ that table is extensible because it is written in the S language. R is faster but less flexible, since that table is programmed in C. It would be useful if R provided a mechanism for extending the derivative table, or barring that, provided a broader table. Currently unsupported mathematical functions of one argument include expm1, log1p,