ACOS logarithmic form

[ljubo]

If I'm interpreting correctly the ACOS illustration from HP 15C Advanced Functions Handbook, page 61, then the positive real axis for x>1 (blue line) is mapped to the positive imaginary axis - means documentation and implementation are consistent. Note that the principal value is denoted with all cap letters (on top of right-hand illustration), where lowercase letters are denoting the multi-value inverse, see explanation on the page 59.