I’m not sure what is going on here so I’m editing this until I have a better fix on it:
On my install of Mandriva the _hypot function used in
is not defined.
mathinline.h defines hypot, and some headers seem to suggest that _hypot should be aliased to hypot, but I haven’t yet managed to follow the linking order to find out if they are ever used or obsolete. Either way, a brute force alias of _hypot to hypot got me out of trouble.