[Help-gsl] gsl blas idamax

[Andrew Makhorin]

Hello,

Maybe some one could help me.

If I call gsl blas idamax as follows:

   double x[3] = { 11, 33, 22 };
   . . .
   i = cblas_idamax(3, x, 1);

then which returned value is correct, 1 or 2 ? Gsl blas idamax returns
1 that corresponds to 0-base indexing. However, AFAIK, some C blas
implementations (e.g. IBM ESSL) follow Fortran conventions; otherwise,
the standard blas tests would fail.

I also would like to note that in case of n = 0 gsl blas idamax
(see blas/source_iamax_r.h) returns 0 rather than -1. Probably it is
a bug, since the reference Fortran version of idamax returns 0 in this
case.

Thanks,

Andrew Makhorin