On 18/06/2010 9:59 AM, David Scott wrote:
I have no experience with incorporating Fortran code and am probably
doing something pretty stupid.
I want to use the following Fortran subroutine (not written by me) in
the file SSFcoef.f
subroutine SSFcoef(nmax,nu,A,nrowA,ncolA)
implicit double precision(a-h,o-z)
implicit integer (i-n)
integer l,i,nmax
double precision nu,A(0:nmax,0:nmax)
A(0,0) = 1D0
do l=1,nmax
do i=1,l-1
A(l,i) = (-nu+i+l-1D0)*A(l-1,i)+A(l-1,i-1)
end do
A(l,0) = (-nu+l-1D0)*A(l-1,0)
A(l,l) = 1D0
end do
return
end
I created a dll (this is windows) using R CMD SHLIB SSFcoef.f
Then my R code is:
### Load the compiled shared library in.
dyn.load("SSFcoef.dll")
### Write a function that calls the Fortran subroutine
SSFcoef <- function(nmax, nu){
.Fortran("SSFcoef",
as.integer(nmax),
as.integer(nu)
)$A
}
SSFcoef(10,2)
which when run gives
> SSFcoef(10,2)
NULL
I am pretty sure the problem is that I am not dealing with the matrix A
properly. I also tried this on linux and got a segfault.
Can anyone supply the appropriate modification to my call (and possibly
to the subroutine) to make this work?
Two problems:
Your subroutine takes 5 arguments, you're only passing two.
You didn't name your arguments, but are trying to retrieve A by name.
So this will get you closer (it's untested, so there might still be
problems...):
SSFcoef <- function(nmax, nu){
.Fortran("SSFcoef",
as.integer(nmax),
as.integer(nu),
A = numeric((nmax+1)^2),
nrowA = as.integer(nmax+1), # These are unused...
ncolA = as.integer(nmax+1)
)$A
}
Duncan Murdoch
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