TIR function

[cimento cola]

Wonder if anyone can help.
Does anyone know how excel calculates, meaning which formula, th TIR
function?
Thanks in advance.

 

[Tom Ogilvy]

What it the region/language for sexmagnet ISP. There is no TIR function for
English Excel. Basically, however, if you can't find it in help, there is
no explanation of how it calculates.