Complex arg-trig functions

[Bruce Evans]

On Fri, 21 Sep 2012, Stephen Montgomery-Smith wrote:

> I did put in the pio2_hi etc stuff in before this email telling me to hold 
> off.
>
> I assume you still want pio2_hi etc stuff in catanh.  There is it still 
> m_pi_2.  I was thinking
> poi2_hi + (tiny + pio2_lo)
> or maybe declaring pio2_lo as volatile and using
> pio2_hi + pio2_lo

I have the latter.

m_pi_2 (better pio2) could be #defined as (pio2_hi + pio2_lo), but I
want to avoid this obfuscation.

Bruce