extern variables in <math.h>

[Peter Sherwood]

Environment: Pentium II 450, Red Hat Linux 7.0

I accidentally left out the declaration for an integer j1 in my C function.
I did not get an "undeclared identifier" error from gcc; instead I got a
warning that I was making an integer from a pointer without a cast. On
investigating, I found the following code inserted by #include <math.h>:

extern double j0 ( double); extern double __j0 ( double);
extern double j1 ( double); extern double __j1 ( double);
extern double jn (int, double); extern double __jn (int, double);
extern double y0 ( double); extern double __y0 ( double);
extern double y1 ( double); extern double __y1 ( double);
extern double yn (int, double); extern double __yn (int, double);

These names interfere with my namespace, and as far as I can tell they
should not be there; there are no functions in either the C Standard
Library nor in the documentation for glibc.