When lapack and blas libraries are linked, the specification of routines could depend on the machine environment. The variation could be capital or small letter, or with or without of the underscore. To choose a proper name of lapack and blas routines on your computer environment, you can specify an option by -Df77, -Df77_, -Df77__, -DF77, -DF77_, or -DF77__. If the capital letter is needed in calling the lapack routines, then choose 'F', and choose a type of the underscore by none, '_', or '__'. The default set is -Df77_.