Raymond Filiatreault wrote:
I did mention that the two formulas were FUNDAMENTALLY different. One uses the ACOS function of "z" while the other uses the ACOSH function of "z".
Complex triginometric and hyperbolic functions are closely related (as are their inverses), ie.: sin(z) = (exp(i*z)-exp(-i*z))/(2*i) sinh(z) = (exp(z)-exp(-z))/2 or your examples: acos(z) = -i * log(z+sqrt(z*z-1)) acosh(z) = log(z+sqrt(z*z-1)) All complex functions available in Fractint are listed like above somewhere in the online help, but as my use of the word "somewhere" indicates, some of these things are a bit hard to find if they are not part of the immediate help topic (reached by <F1>). A good idea is to run Fractint with the command line parameter "makedoc", which dumps the whole online help as one big ASCII text file named "fractint.doc" onto your harddisk... The functions are on page 185 and 186... Regards, Gerald