R help - Feb 2012 - Converting a function from Splus to R

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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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 Hern?ndez <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)
> }
>
> --
> View this message in context:
http://r.789695.n4.nabble.com/Converting-a-function-from-Splus-to-R-tp4431416p4431416.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

On 29-02-2012, at 14:02, Freddy Hern?ndez wrote:
> 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)
> }
I know nothing of S.
But why don't you just try   "0.e0" and "2.e0" or better
0 and 2?
I'm guessing that these are numbers.

Berend