search for: solns

If I have matrics as follows: > a <- c(1,1,0,0) > b <- c(4,4,0,0) > c <- c(3,5,5,6) How can I use R code to solve the equation ax^2+bx+c=0. thanks! yuying shi [[alternative HTML version deleted]]

for the googleable r-help archives, I thought I would post what I wrote into my .Rprofile to automatically set some system information. the most relevant aspect is the determination of mc.cores. this is useful when users want to use the parallel package options(uname= system("uname", intern=TRUE)) options(os= if (getOption("uname")=="Darwin") "osx"

Dear R wizards--- I have a wrapper on mclapply() that makes it a little easier for me to do multiprocessing. (Posting this may make life easier for other googlers.) I pass a data frame, a vector that tells me what rows should be recomputed, and the function; and I get back a vector or matrix of answers. d <- data.frame( id=1:6, val=11:16 ) loc <- c(TRUE,TRUE,FALSE,TRUE,FALSE,TRUE)

Hi, sorry, I'm an idiot.. and I know I'm missing something stupid.. I thought if we solve an underdetermine system with QR, my soln is: min ||x|| (L2 sense) such that Ax = b then say i have: > w <- matrix(c(1, 5), ncol=2) > sw = 2 > qrW = qr(t(w) %*% w) > qr.coef(qrW, t(w) %*% sw) [,1] [1,] 2 [2,] NA but we also have soln (0, 2/5) which obviously has a

dear R readers---I thought I would post the following snippet of R code that makes by() like operations easier and faster on multicore machines for R novices and amateurs. I hope it helps some. YMMV. feel free to ignore. PS: I wish R had a POD-like documentation system for end users that are not writing full libraries. because it does not, I did not provide documentation ala '?mc.by'.

Hi, I have a problem sorting and selecting entries within a data-frame and I don't know if it is possible to solve it with R ... (probably yes, but I have no idea how). Following Data; row1 row2 a 12 pos NA a 3 neg NA a 5 neg NA a 11 pos NA I want to extract the values in row 2 in the lines with an "a" in row1. But I want to have two vectors: vector x with all

...unt = as.integer(x.count), objective = as.double(objective), const.count = as.integer(const.count), constraints = as.double(constraints), int.count = as.integer(int.count), int.vec = as.integer(int.vec), bin.count = as.integer(bin.count), binary.vec = as.integer(binary.vec), num.bin.solns = as.integer(num.bin.solns), objval = as.double(objval), solution = as.double(solution), presolve = as.integer(presolve), compute.sens = as.integer(compute.sens), sens.coef.from = as.double(sens.coef.from), sens.coef.to = as.double(sens.coef.to), duals = as.double(duals), duals.from...

Hi there R-helpers: I'm having problems with the function ode() found in the package deSolve. It seems that when my state variables are too numerous (>33000 elements), the function throws the following error: Error in vode(y, times, func, parms, ...) : cannot allocate memory block of size 137438953456.0 Gb In addition: Warning message: In vode(y, times, func, parms, ...) : NAs

hi all i m using remote_function , & i need to update two divs at same time (so no :success/:failure).... is there any posiible soln for this thanks rohit --------------------------------- Yahoo! Photos Ring in the New Year with Photo Calendars. Add photos, events, holidays, whatever. -------------- next part -------------- An HTML attachment was scrubbed... URL:

In trying to use simplex() from the boot package, I have run into a situation that doesn't seem like it should be possible. It is claiming that it has solved the LP, but returns a vector of all zeros, which does not satisfy the constraints I passed in. A small example: > ubMatrix <- matrix(c(1,1,-1,0,-1,-1), 3, 2) > ubVector <- c(2,1,-1) > objective <- c(0,1) >

Hello, I use rsync to mirror the home directories of users on a computational cluster for backup purposes. There are users who have single directories containing 12,000+ files. I am using RHEL 4.0 update 4, and the rsync is version: rsync version 2.6.3 protocol version 28 When rsync is deleting the files in a directory with 12,000+ files (i.e. when the directory was removed in the

On 02/10/2018 06:00 AM, r-help-request at r-project.org wrote: > Did you check the gradient? I don't think so. It's zero, so of course > you end up where you start. > > Try > > data.input= data.frame(state1 = (1:500), state2 = (201:700) ) > err.th.scalar <- function(threshold, data){ > > state1 <- data$state1 > state2 <- data$state2 >

Hello, I'm trying to fminimize the following problem: You have a data frame with 2 columns. data.input= data.frame(state1 = (1:500), state2 = (201:700) ) with data that partially overlap in terms of values. I want to minimize the assessment error of each state by using this function: err.th.scalar <- function(threshold, data){ state1 <- data$state1 state2 <- data$state2

Hi John, Am currently running dos mode not graphical mode. Could you have any other method. Hi Ashish, You are correct. qmailtoaster backup file which was around 184 GB in backup.gz type and i have removed .bz2 type file with the same backup/mailbkup directory. After removed .bz2 file it's gone backup.gz also which was 184 GB file. I have run this command locate .gz but couldn't find out

I have two matrix s1 and s2, each of them is 1000*1. and I have two equations: digamma(p)-digamma(p+q)=s1, digamma(q)-digamma(p+q)=s2, and I want to sovle these two equations to get the value of x and y, which are also two 1000*1 matrices. I write a program like this: f <- function(x) { p<- x[1]; q <- x[2]; ((digamma(p)-digamma(p+q)-s1[2,]) )^2 +((digamma(q)-digamma(p+q)-s2[2,]) )^2

Hello, I am fairly new with R and am having trouble finding an optimal group. I checked the help functions for the various optimize commands and it was a little over my head. I have a dataset with 4 columns, name, type, value, and cost. The set consists of a list of people, which have 3 types. I want to choose 6 people, two of each type, and maximize the sum of their values. However, I'm

Hi, (please Cc me) In xyplot (), type = "l" (or one that includes "l", *el*) is (generally) meaningful only when the 'x' variable is sorted. In practice, one either sorts the data frame before hand or writes a tiny panel function which sorts the supplied x and then calls the default panel.xyplot(). Trouble arises when there is a conditional variable as well as a

Hi Chandran, On Thu, Apr 7, 2016 at 10:38 AM, Chandran Manikandan <tech2mani at gmail.com> wrote: > Hi John, > Am currently running dos mode not graphical mode. > Could you have any other method. > > Hi Ashish, > You are correct. > qmailtoaster backup file which was around 184 GB in backup.gz type and i > have removed .bz2 type file with the same backup/mailbkup

  Hi Helpers. I am creating one wrapper VC++ dll for use some simple statistical functions like correlation/covariance for my college project. I have done the following:   I have gone thru R-exts.pdf u r mentioning. I have follwed the steps gievn under topic "The R api: entry points for C code". I have done these things 1) Created vc++ simple dll project. 2)inclued <R.h> in the

I tried optim using the SANN algoithm. To start things out I tried the example of solving the "traveling salesman" problem as given in the documentation. The example works just fine. But if I comment out the line: set.seed(123) # chosen to get a good soln relatively quickly More often than not it doesn't converge to the optimum solution as shown in the example. Alos with trace on