# [R] Converting a function from Splus to R

R. Michael Weylandt michael.weylandt at gmail.com
Wed Feb 29 14:24:55 CET 2012

Change the name to something syntactically valid? The problem is that
you can't (well, you can, but it's ill advised) have variable names
beginning with numbers.  They don't seem to be used much so there
won't be much trouble in that.

Michael

2012/2/29 Freddy Hernández <fhernanb at gmail.com>:
> I have a function written for Splus, when I run it in R I obtain get an error
> because the function has the elements "0.d0" and "2.d0". How can I change it
> to run in R?
>
> The function can be found in page 230 from
>  http://www.stat.wisc.edu/~mchung/teaching/stat471/stat_computing.pdf
>
> Function is as follows:
>
> gauher <- function(n) {# Gauss-Hermite: returns x,w so that
> #\int_-\infty^\infty exp(-x^2) f(x) dx \doteq \sum w_i f(x_i)
> EPS <- 3.e-14
> PIM4 <- .7511255444649425D0
> MAXIT <- 10
> m <- trunc((n+1)/2)
> x <- w <- rep(-1,n)
> for (i in 1:m) {
> if (i==1) {
> z <- sqrt(2*n+1)-1.85575*(2*n+1)^(-.16667)
> } else if(i==2) {
> z <- z-1.14*n^.426/z
> } else if (i==3) {
> z <- 1.86*z-.86*x[1]
> } else if (i==4) {
> z <- 1.91*z-.91*x[2]
> } else {
> z <- 2.*z-x[i-2]
> }
> for (its in 1:MAXIT) {
> p1 <- PIM4
> p2 <- 0.d0
> for (j in 1:n) {
> p3 <- p2
> p2 <- p1
> p1 <- z*sqrt(2.d0/j)*p2-sqrt((j-1)/j)*p3
> }
> pp <- sqrt(2.d0*n)*p2
> z1 <- z
> z <- z1-p1/pp
> if(abs(z-z1) <= EPS) break
> }
> x[i] <- z
> x[n+1-i] <- -z
> w[i] <- 2/(pp*pp)
> w[n+1-i] <- w[i]
> }
> list(x=x,w=w)
> }
>
> --
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