[R] Strange behavior using .Fortran

[Peter Dalgaard BSA]

"Uli Flenker; Raum 704" <uli at biochem.dshs-koeln.de> writes:

> Hello everybody,
> 
> I observed some strange behavior of R (0.64.1/Linux 2.0.25) when trying
> to use FORTRAN-libraries.
> 
> I downloaded "ALGORITHM AS 304" from StatLib. All I changed  at
> the code, was to substitute "REAL"-routines by "DOUBLE PRECISION".
> 
....
> Here is the prototype of R-code that I used ...
> 
> > dyn.load("/path-to-lib/rtest.o")
> 
> > fisher.ts.test<-function(x,y){
> 
>    nx<-length(x)
>    ny<-length(y)
> 
>          
>    ftr.out<-..Fortran("fisher",
              ??

>                      as.real(x),
>                      as.integer(nx),
>                      as.real(y),
>                      as.integer(ny),
>                      as.integer(0),
>                      as.integer(0),
>                      as.real(0.0),
>                      as.integer(0))
> 
> return(ftr.out)
> }
> 
> 
> Loading the code was no problem. Now, here is what I obtained when using
> it:
> 
> > a<-c(18,19,25)
> > b<-c(20,29,29,30,31,31,31)
> 
> > fisher.ts.test(a,b)
> [[1]]
> [1] 18 19 25
> 
> [[2]]
> [1] 3
> 
> [[3]]
> [1] 20 29 29 30 31 31 31
...
> ... which are the correct results.
> 
> 
> But invoking the thing exchanging "a" and "b" gives the following strange
> things ...
> 
> > fisher.ts.test(b,a)
> [[1]]
> [1] 31 31 31 30 31 31 31
...
> 
> Furthermore ...
> 
> > x<-round(rnorm(3,10),2)
> > y<-round(rnorm(7,5),2)
> > fisher.ts.test(x,y)
> Process R segmentation fault at Thu Jul 15 19:08:01 1999

Hmm... I can't offhand spot any obvious blunders. Are you sure you got
*all* reals converted to double in the Fortran routines? If you have
data that reliably causes segfault, try running it with R -d gdb (use
-g for the compilation) to get the exact line where it crashes. And,
btw, eliminate optimizer errors by compiling without -O.

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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