5.004_02: Complex/Trig: update

5.004_02: Complex/Trig: update

The following patches do not fix actual grave errors but they do:

- make the code more robust (more discontinuities catched)
  (e.g. atan(-i), atanh(-1))
- make the results agree on signs and/or conjugate forms with the
  results MATLAB gives: the results were already correct thanks to
  the periodicity of trig funcs but now they are also consistent.
  (e.g. acos(x) did have an unnecessary discontinuity at x = 0)
- for some pure real arguments short-circuit the calculation
  to avoid rounding errors (which make epsilons appear where
  clear zeros should reign)

Tested on NetBSD 1.2G i686, Linux 2.0.25 i686, Digital UNIX 4.0 EV56.

p5p-msgid: 199708081842.VAA31214@alpha.hut.fi