Dear R users,
I have to call fortran program from within R (R 2.8.1 on ubuntu 8.10
machine).
Suppose I have a fortran code like this (this is only a toy model, my
working model is far more complex, but input/output is similar)
DOUBLE PRECISION FUNCTION model(times, alfa, beta)
DOUBLE PRECISION alfa, beta, times
model=beta*sin(times)+alfa*cos(times)
END FUNCTION
which is saved as model.f.
I wrote a wapper like this (saved as wrapper.f)
SUBROUTINE model_wrapper(times, alfa, beta, answer)
DOUBLE PRECISION times, alfa, beta, answer
EXTERNAL model
answer = model(times, alfa, beta)
END SUBROUTINE
Then I compiled all this stuff
g77 -fno-second-underscore -c -fPIC model.f
g77 -fno-second-underscore -c -fPIC wrapper.f
g77 -fno-second-underscore -shared -o model.so model.o wrapper.o
From within R
dyn.load('model.so')
model <- function(times, alfa, beta) {
returned_data = .Fortran('model_wrapper', times=as.double(times),
alfa=as.double(alfa),
beta=as.double(beta), result=double(1))
return(returned_data) }
# example run
test_1<-model(1.0,0.2,0.3)
which gives
test_1$times
[1] 1.0
$alfa
[1] 0.2
$beta
[1] 0.3
$result
[1] 147456887
where $result is clearly wrong.
I suppose I made some mistake with the handling of data types, but I am
not able to figure out where.
Can someboby help me?
Giacomo
--
-------------------------------------------------------
Giacomo Santini PhD
Dipartimento di Biologia Evoluzionistica "Leo Pardi"
Universita' degli Studi di Firenze
Via Romana 17
I-50125 Firenze
Italy
Tel: +39 055 2288288 (DBE) - +39 0574 447727 (CESPRO)
Fax: +39 055 2288289
www.dbe.unifi.it/santini
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