similar to: Solve f(x) = 0

Hi! I'm trying to start a credibility estimation study with a coule of data sets that are created for SAS. The data sets are saved as ".sas7bndx" and ".sas7bdat". I've tried reading them to R with the function 'read.xport' but this returns the error message 'Error in lookup.xport(file) : unable to open file'. Are there any other functions that one

Hi! I've just begun writing a program that searches for the minimum of a function with golden section search. In order to do this in a nice way I need a function that takes a function name and an argument and returns the function value for that argument, i .e just like Matlab's 'feval'. Is there any? Thanks before hand! Best regards, Fredrik Thuring, Codan Insurance A/S

Hi! I have a few questions concerning reading of tables from R to other programs. My main question is if it’s even possible to read a table created in R (with the functions data.frame and save) to Excel (or maybe SAS) and if so how does one do this? If I just mark the table in R and copy-paste to Excel the whole table ends up in one single cell, (of course). My goal is to

Dear Sir or Madam, I'm wondering if there is any routine or argument in the function 'glm.fit' that makes it handle NA's. The function 'glm' can handle NA's but I can't make make it work (or find anything written on this in the help files) with 'glm.fit'. Is it even possible in'glm.fit'? How? Thanks before hand, Fredrik Thuring, Business Researcher

Hi! Is there a way of handling NA?s in the matrix multiplication function '%*%'? I cant find anything concerning this in the help files. I?m thinking of some sort of setting such as na.rm=T. Thanks before hand to anyone how can help me! Fredrik Thuring, Junior Business Researcher __________________________________ Codan Forsikring, Gammel Kongevej 60, DK-1790 Copenhagen V tel: +45 33 55

Hi, I want find all roots for the following polynomial : a <- c(-0.07, 0.17); b <- c(1, -4); cc <- matrix(c(0.24, 0.00, -0.08, -0.31), 2); d <- matrix(c(0, 0, -0.13, -0.37), 2); e <- matrix(c(0.2, 0, -0.06, -0.34), 2) A1 <- diag(2) + a %*% t(b) + cc; A2 <- -cc + d; A3 <- -d + e; A4 <- -e fn <- function(z) { y <- diag(2) - A1*z - A2*z^2 - A3*z^3 - A4*z^4

Dear List, I know this is not the first post on this topic, but I need basic help I guess. Assuming the simple case of two lines with one intercept, how can I make R calculate this intercept, NOT using locator(). par (xaxs="i", yaxs="i") plot( 1, bty="n" ,xlim=c(0,300) , ylim=c(0,300) , xlab="X", ylab="Y") curve(100-0.5*x, -50,250, add=T,

Hi there, I would like to solve the following equation in R to estimate 'a'. I have the amp, d, x and y. amp*y^2 = 2*a*(1-a)*(-a*d+(1-a)*x)^2 test data: amp = 0.2370 y= 0.0233 d= 0.002 x= 0.091 Can anyone suggest how I can set this up? Thanks, Diviya [[alternative HTML version deleted]]

Hi all, This is probably a blindingly obvious question: Why does it matter in the uniroot function whether the f() values at the end points that you supply are of the same sign? For example: f <- function(x,y) {y-x^2+1} #this gives a warning uniroot(f,interval=c(-5,5),y=0) Error in uniroot(f, interval=c(-5, 5), y = 0) : f() values at end points not of opposite sign #this doesn't give a

Dear friends - occurring in Windows R2.6.2 I am modeling physical chemistry in collaboration with a friend who has preferred working in Excel. I used uniroot, and find a solution to a two buffer problem in acid-base chemistry which I believe is physiologically sensible. Using "goal seek" in Excel my friend found another plausible root, quite close to zero, and a plot of the function

Dear list, Did anybody have something like multiroot(), similar to uniroot() only for several varibles/function? I know the difficulty several varibles bring. But for nice functions, it can be useful. We are thinking of writing one....I thought to ask first. Mai Zhou -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read

Hello, I have search on R website but do not find any solution. I would like to know if R has some functionalities to produce analytical results of equation. or more generally if it contains some functions to simplify equation. For example: I would like to obtain x1 from: x1+x2=8 (x1=8-x2) x1^2+x2=8 (x1=sqrt(8-x2)) Is is possible in R ? if not, do you know a (free) software that could do the

Hi, I'm having trouble converting code from MATLAB to R; I want to find the equivalence to MATLAB's function 'fsolve'. I've tried 'nlm', on the squared argument, in R but i did not get the same results. Thankful if helped. Best regards, Martin Englund ------------------------------------------------------------------------------ This e-mail and any attachment may

I need to solve a system of non-linear fourth-order differential equations. Is there a command which solves this system? Thanks in advance.

Hello, I have a problem finding a root of a function, which I define like this: tuki <- function(u, x, a, lambda){ if((lambda%%1>0) & u<0) {u<-(u+0i)} f <- Re(x-(a*(u)^lambda-(1-(u))^lambda)/lambda) f } What I want to do is to find the root, but without specifying the interval within which to search for it. I can do it easily in MATLAB with fsolve() or fzero() functions. I

? Mon, 6 Nov 2023 17:53:49 +0100 Troels Ring <tring at gvdnet.dk> ?????: > Hence I wonder if I could somehow have non linear regression to find > the 3 pK values. Below is HEPESFUNC which delivers charge in the > fluid for known pKs, HEPTOT and SID. Is it possible to have > root-finding in the formula with nls? Sure. Just reformulate the problem in terms of a function that

With main R releases only happening yearly in spring, now is good time to consider *and* discuss new features for what we often call "R-devel" and more officially is R Under development (unstable) (.....) -- "Unsuffered Consequences" Here is one such example I hereby expose to public scrutiny: A few minutes ago, I've committed the following to R-devel (the

Hi everyone. I have a problem that I have been unable to determine either the best way to proceed and why the methods I'm trying to use sometimes fail. I'm using the pf() function in an optimization function to find a noncentrality parameter that leads to a specific value at a specified quantile. My goal is to have a general function that returns the noncentrality parameter that

Dear friends - I have a function for the charge in a fluid (water) buffered with HEPES and otherwise only containing Na and Cl so that [Na] - [Cl] = SID (strong ion difference) goes from -1 mM to 1 mM. With known SID and total HEPES concentration I can calculate accurately the pH if I know 3 pK values for HEPES by finding the single root with uniroot Now, the problem is that there is some

Hi, I'd like to find which values of x will give me a y. In other words, in the example of a gaussian curve, I want to find the values of x that will give me a density, let's say, of 0.02. curve(((1/(sqrt(2*pi)*10))*exp(-((x-50)^2)/(2*10^2))),xlim=c(0,100)) Thanks for any help, Antonio Olinto ------------------------------------------------- WebMail Bignet - O seu provedor do