Speaking only from the confines of my own narrow little mind, I really really don't like over loading undefined. It is far more useful at least for me, to deal with things like +/- infinity, NAN and other similar such. One of the first things I did when first using a math chip (AMD 9511 or AMD 9512) was to write the C to ASSM interface to handle errors and exceptions in general-- typically preserve and return the status word. More to the point, since there are a lot of ways to mess the math, I'd rather have more information than less! just my 0.02$ worth hsm