Thanks Berend, I got curious and checked your package, and no errors. However, two open questions:

1. You invoke the call to dgemv from a Fortran subroutine that is called from a C function, which in turn is called in R by .Call. I go directly via .Fortran, no C involved, except by "base R", see 2. below.

2. I am still wondering why your route gets away with avoiding "the 12th hidden argument" FCLEN, see R-devel/include/R_ext/BLAS.h:

F77_NAME(dgemv)(const char *trans, const int *m, const int *n,
                const double *alpha, const double *a, const int *lda,
                const double *x, const int *incx, const double *beta,
                double *y, const int *incy FCLEN);

when my direct route doesn't?


On 2019-09-12 09:15, Berend Hasselman wrote:

I have checked my package nleqslv which uses dgemv only from Fortran, on 
Kubuntu 18.04 with the development version of R.
No errors or problems.


On 12 Sep 2019, at 08:57, Berend Hasselman <> wrote:

I have tried what I proposed in a virtual Kubuntu 18.04 which uses gfortran 7.4.
I used the latest development version of R.

It worked just as on macOS.


On 11 Sep 2019, at 22:07, Göran Broström <> wrote:


I do not think this works with gfortran 7+. I am calling the BLAS subroutine 
dgemv from Fortran code in my package eha, and the check (with R-devel) gives:

gmlfun.f:223:1: warning: type of ‘dgemv’ does not match original declaration 
     &     score, ione)
/home/gobr0002/R/src/R-devel/include/R_ext/BLAS.h:107:1: note: type mismatch in 
parameter 12
F77_NAME(dgemv)(const char *trans, const int *m, const int *n,

Type of a Fortran subroutine is matched against type of a C function?! My 
conclusion is that it is impossible to call a BLAS subroutine with a character 
parameter from Fortran code (nowadays). Calling from C code is fine, on the 
other hand(!).

I have recently asked about this on R-pkg-devel, but not received any useful 
answers, and my submission to CRAN is rejected. I solve it by making a personal 
copy of dgemv and changing the character parameter to integer, and adding Jack 
Dongarra, Jeremy Du Croz, Sven Hammarling, and Richard Hanson as authors of 
eha. And a Copyright note, all in the DESCRIPTION file. Ugly but what can I do 
(except rewriting the Fortran code in C with f2c)?


On 2019-09-11 21:38, Berend Hasselman wrote:
The Lapack library is loaded automatically by R itself when it needs it  for 
doing some calculation.
You can force it to do that with a (dummy) solve for example.
Put this at start of your script:
# dummy code to get LAPACK library loaded
X1 <- diag(2,2)
x1 <- rep(2,2)
# X1;x1
z <- solve(X1,x1)
followed by the rest of your script.
You will get a warning (I do) that  "passing a character vector  to .Fortran is not 
On other systems this may gave fatal errors. This is quick and very dirty. 
Don't do it.
I believe there is a better and much safer way to achieve what you want.
Here goes.
Create a folder (directory) src in the directory where your script resides.
Create a wrapper for "dpbtrf" file in a file xdpbtrf.f that takes an integer 
instead of character
c intermediate for dpbtrf
c      .. Scalar Arguments ..
      integer         kUPLO
      INTEGER         INFO, KD, LDAB, N
c  .. Array Arguments ..
      character UPLO
c     convert integer argument to character
      if(kUPLO .eq. 1 ) then
          UPLO = 'L'
          UPLO = 'U'
      call dpbtrf(UPLO,N,KD,AB,LDAB,INFO)
Instead of a character argument UPLO it takes an integer argument kUPLO.
The meaning should be obvious from the code.
Now create a shell script in the folder of your script to generate a dynamic 
library to be loaded in your script:
# Build a binary dynamic library for accessing Lapack dpbtrf
# syntax checking
echo Strict syntax checking
echo ----------------------
gfortran -c -fsyntax-only -fimplicit-none -Wall src/*.f || exit 1
R CMD SHLIB --output=${SONAME} src/*.f ${LAPACK} || exit 1
To load the dynamic library  change your script into this
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) <- .Fortran("xdpbtrf", kUPLO=1L, N = as.integer(n),
                            KD = 1L, AB = AB, LDAB = 2L, INFO = 
and you are good to go.
You should always do something  as described above when you need to pass 
character arguments to Fortran code.
All of this was tested and run on macOS using the CRAN version of R.
Berend Hasselman
On 11 Sep 2019, at 15:47, Giovanni Petris <> wrote:

Sorry for cross-posting, but I realized my question might be more appropriate 
for r-devel...

Thank you,

From: R-help <> on behalf of Giovanni Petris 
Sent: Tuesday, September 10, 2019 16:44
Subject: [R] Calling a LAPACK subroutine from R

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 <- .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
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

[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!

Giovanni Petris

Giovanni Petris, PhD
Director of Statistics
Department of Mathematical Sciences
University of Arkansas - Fayetteville, AR 72701

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