G'day Dominick,
On Mon, 5 Mar 2012 19:21:01 -0500
Dominick Samperi <[email protected]> wrote:
> Section 5.2 of the R manual (on Extending R) says that only
> FORTRAN subroutines can be called (not functions), probably
> because of the non-standard way the compilers map FORTRAN
> function names to symbols in the DLL.
Section 5.2 deals with calling C/FORTRAN code from R via .C()
or .Fortran(), and is not directly relevant to the question on how to
call FORTRAN code from C code. :)
> This is consistent with the interface prototype for the BLAS
> routine zdotc contained in <R>/include/R_ext/BLAS.h, namely,
>
> BLAS_extern Rcomplex
> F77_NAME(zdotc)(Rcomplex * ret_val, int *n,
> Rcomplex *zx, int *incx, Rcomplex *zy, int *incy);
>
>[...]
>
> On the other hand, this is not consistent with the standard
> FORTRAN definition for zdotc that is contained in
> <R>/src/extra/blas/cmplxblas.f, where the first argument is
> n, not ret_val.
This seems to be indeed inconsistent and, presumably, a bug. Applying
the attach patch to R's development version (compiles, installs and
passes all checks with this patch), and changing in your code the line
F77_CALL(zdotc)(&ret_val, &n, zx, &incx, zy, &incy);
to
ret_val = F77_CALL(zdotc)(&n, zx, &incx, zy, &incy);
produces the expected output.
> Consequently, it is not clear where the wrapper
> is defined that is called via the prototype.
The F77_xxxx macros seem to be defined in <R>/include/R_ext/RS.h, and
their sole purpose seems to be to append a _ to the argument if
needed.
Cheers,
Berwin
Index: src/include/R_ext/BLAS.h
===================================================================
--- src/include/R_ext/BLAS.h (revision 58604)
+++ src/include/R_ext/BLAS.h (working copy)
@@ -245,10 +245,10 @@
F77_NAME(zcopy)(int *n, Rcomplex *zx, int *incx,
Rcomplex *zy, int *incy);
BLAS_extern Rcomplex
- F77_NAME(zdotc)(Rcomplex * ret_val, int *n,
+ F77_NAME(zdotc)(int *n,
Rcomplex *zx, int *incx, Rcomplex *zy, int *incy);
BLAS_extern Rcomplex
- F77_NAME(zdotu)(Rcomplex * ret_val, int *n,
+ F77_NAME(zdotu)(int *n,
Rcomplex *zx, int *incx, Rcomplex *zy, int *incy);
BLAS_extern void
F77_NAME(zdrot)(int *n, Rcomplex *zx, int *incx, Rcomplex *zy,
Index: doc/manual/R-exts.texi
===================================================================
--- doc/manual/R-exts.texi (revision 58604)
+++ doc/manual/R-exts.texi (working copy)
@@ -12229,7 +12229,7 @@
The @R{} for Windows installers have for a long time allowed the value
of @code{R_HOME} to be recorded in the Windows Registry: this is
-optional but selected by default. @emph{Where} is it is recorded has
+optional but selected by default. @emph{Where} it is recorded has
changed over the years to allow for multiple versions of @R{} to be
installed at once, and to allow 32- and 64-bit versions of @R{} to be
installed on the same machine.
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