[R] Converting a function from Splus to R

[William Dunlap]

1.0d+0 is Fortran (not C) for a double precision value,
1.0 * 10^0.

1.0e+0 is Fortran for a single precision value, 1.0 * 10^0
and C for a double precision value.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Prof Brian
> Ripley
> Sent: Wednesday, February 29, 2012 5:41 AM
> To: R. Michael Weylandt
> Cc: r-help at r-project.org; Freddy Hernández
> Subject: Re: [R] Converting a function from Splus to R
> 
> On 29/02/2012 13:24, R. Michael Weylandt wrote:
> > 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.
> 
> I think that 2.0d0 is someone translating C into R. Just use 2 .  In R,
> 2 is a double precision floating-point constant: in C and (recent
> S-PLUS) it is integer and you need to use 2.0 .
> 
> > 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)
> >> }
> >>
> >> --
> >> 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.
> >
> > ______________________________________________
> > 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.
> 
> 
> --
> Brian D. Ripley,                  ripley at stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
> 
> ______________________________________________
> 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.