On 12/07/2008 3:56 AM, Hao Ren Sr wrote:
Hi,
I have an error happened when I use exp() in my Fortran code. My Fortran
code is
SUBROUTINE f(n,c)
REAL, INTENT(IN) :: n(10)
REAL, INTENT(OUT) :: c(10)
INTEGER :: k
DO k=1, 10
c(k) = exp( n(k) )
END DO
END
I compiled the fortran code as a dll
Rcmd SHLIB -o f.dll f.f -L -lacml
Then I loaded the dll file to R, and try some number
dyn.load("C:/Program Files/R/R-2.7.1/bin/code/f.dll")
.Fortran("f",as.real(c(1:10)),A=real(10))
[[1]]
[1] 1 2 3 4 5 6 7 8 9 10
$A
[1] 17066.21 58265.20 179948.41 390001.06 576529.12 0.00 0.00
[8] 0.00 0.00 0.00
I tried to figur out what happened, but confused. Any suggestion?
real and as.real set double precision values in R. In Fortran, the REAL
type is single precision.
The most efficient thing to do is to declare n and c to be double
precision in your Fortran code, but you could use single and as.single
in R to have it automatically convert back and forth. There is no
single precision type in R, so this is inefficient.
Duncan Murdoch
Thanks
Hao Ren
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and provide commented, minimal, self-contained, reproducible code.
