[Rd] Problem with function in fortran 95

Fabio Mathias Corrêa fabio.ufla at yahoo.com.br
Wed Aug 12 13:32:58 CEST 2009

```I am writing a function in fortran 95, but the intrinsic function MATMUL is not working properly. Here's an example.

SUBROUTINE mymult(x,y,res,m,n)
IMPLICIT NONE
INTEGER :: m,n
REAL :: x, y, res
DIMENSION :: x(m,n), y(n,m), res(m,m)
res = MATMUL(x,y)
END SUBROUTINE mymult

R CMD SHLIB mat.f95

In R:

x   <- matrix(1:20,5)
l   <- nrow(x)
c   <- ncol(x)
y   <- matrix(20:1,c)
res <- matrix(0,l,l)
dim(x)
dim(y)
dim(res)
l
c
.Fortran("mymult", x,y,res,l,c)

[[1]]
[,1] [,2] [,3] [,4]
[1,]    1    6   11   16
[2,]    2    7   12   17
[3,]    3    8   13   18
[4,]    4    9   14   19
[5,]    5   10   15   20

[[2]]
[,1] [,2] [,3] [,4] [,5]
[1,]   20   16   12    8    4
[2,]   19   15   11    7    3
[3,]   18   14   10    6    2
[4,]   17   13    9    5    1

[[3]]
[,1] [,2] [,3] [,4] [,5]
[1,]    0    0    0    0    0
[2,]    0    0    0    0    0
[3,]    0    0    0    0    0
[4,]    0    0    0    0    0
[5,]    0    0    0    0    0

[[4]]
[1] 5

[[5]]
[1] 4

Linux Ubuntu 8.04 and use compiler gfortran 4.2.
The problem is the compiler?

Thanks!

Fábio Mathias Corrêa
Estatística e Experimentação Agropecuária/UFLA
Brazil

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