On 06-03-2012, at 01:21, Dominick Samperi wrote:
> Hello,
>
> I am trying to call the BLAS Level1 function zdotc from R via
> a .C call like this:
>
> #include "R.h"
> #include "R_ext/BLAS.h"
>
> void testzdotc() {
> Rcomplex zx[3], zy[3], ret_val;
>
> zx[0].r = 1.0; zx[0].i = 0.0;
> zx[1].r = 2.0; zx[0].i = 0.0;
> zx[2].r = 3.0; zx[0].i = 0.0;
>
> zy[0].r = 1.0; zy[0].i = 0.0;
> zy[1].r = 2.0; zy[0].i = 0.0;
> zy[2].r = 3.0; zy[0].i = 0.0;
>
> int n=3, incx=1, incy=1;
> F77_CALL(zdotc)(&ret_val, &n, zx, &incx, zy, &incy);
> Rprintf("ret_val = %f, %f\n", ret_val.r, ret_val.i);
> }
>
> This does not work. When I run '.C('testzdotc')' there is
> typically a delay for a second or so, then I get: 0.0, 0.0
> instead of the correct ans: 14.0, 0.0.
I tried calling zdotc through an intermediate Fortran routine hoping it would
solve your problem.
Above C routine changed to
<code>
#include "R.h"
void F77_NAME(callzdotc)(Rcomplex *, int *, Rcomplex *, int *, Rcomplex *, int
*);
void testzdotc() {
Rcomplex zx[3], zy[3], ret_val;
zx[0].r = 1.0; zx[0].i = 0.0;
zx[1].r = 2.0; zx[0].i = 0.0;
zx[2].r = 3.0; zx[0].i = 0.0;
zy[0].r = 1.0; zy[0].i = 0.0;
zy[1].r = 2.0; zy[0].i = 0.0;
zy[2].r = 3.0; zy[0].i = 0.0;
int n=3, incx=1, incy=1;
F77_CALL(callzdotc)(&ret_val, &n, zx, &incx, zy, &incy);
Rprintf("ret_val = %f, %f\n", ret_val.r, ret_val.i);
}
</code>
The fortran subroutine is
<code>
subroutine callzdotc(retval,n, zx, incx, zy, incy)
integer n, incx, incy
double complex retval, zx(*), zy(*)
external double complex zdotc
retval = zdotc(n, zx, incx, zy, incy)
return
end
</code>
Made a shared object with
R CMD SHLIB --output=dozdot.so callzdotc.f czdot.c
and ran
dyn.load("dozdot.so")
.C("testzdotc")
with the result 0.0, 0.0
I would've expected this to give the correct result.
Berend
Mac OS X 10.6.8
R2.14.2
Using reference Rblas.
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