[R] Calling a LAPACK subroutine from R

[Göran Broström]

Giovanni,

you are trying to open a can of worms. Se recent discussions on 
R-pkg-devel, Writing R Extensions, and the help page for .Fortran.

Best, Göran

On 2019-09-10 23:44, Giovanni Petris wrote:
> 
> Hello R-helpers!
> 
> I am trying to call a LAPACK subroutine directly from my R code using .Fortran(), but R cannot find the symbol name. How can I register/load the appropriate library?
> 
>> ### AR(1) Precision matrix
>> n <- 4L
>> phi <- 0.64
>> AB <- matrix(0, 2, n)
>> AB[1, ] <- c(1, rep(1 + phi^2, n-2), 1)
>> AB[2, -n] <- -phi
>> round(AB, 3)
>        [,1]  [,2]  [,3] [,4]
> [1,]  1.00  1.41  1.41    1
> [2,] -0.64 -0.64 -0.64    0
>>
>> ### Cholesky factor
>> AB.ch <- .Fortran("dpbtrf", UPLO = 'L', N = as.integer(n),
> +                  KD = 1L, AB = AB, LDAB = 2L, INFO = as.integer(0))$AB
> Error in .Fortran("dpbtrf", UPLO = "L", N = as.integer(n), KD = 1L, AB = AB,  :
>    Fortran symbol name "dpbtrf" not in load table
>> sessionInfo()
> R version 3.6.0 (2019-04-26)
> Platform: x86_64-apple-darwin18.5.0 (64-bit)
> Running under: macOS Mojave 10.14.6
> 
> Matrix products: default
> BLAS/LAPACK: /usr/local/Cellar/openblas/0.3.6_1/lib/libopenblasp-r0.3.6.dylib
> 
> locale:
> [1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
> 
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
> 
> loaded via a namespace (and not attached):
> [1] compiler_3.6.0 tools_3.6.0
> 
> Thank you in advance for your help!
> 
> Best,
> Giovanni Petris
> 
> 
> 
> --
> Giovanni Petris, PhD
> Professor
> Director of Statistics
> Department of Mathematical Sciences
> University of Arkansas - Fayetteville, AR 72701
> 
> 
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