# Function inversion

1. Mar 13, 2008

### NoobixCube

What is the criteria to know whether a function may be inverted into an elementary functional form?

2. Mar 13, 2008

### HallsofIvy

Staff Emeritus
Define "elementary functional form".

Any function that is "one to one" from set A onto set B then can be inverted ito an inverse function from B to A.

Do you consider "ln(x)" and "ex" "elementary functional forms"? Since a common definition of "ln(x)" is "the inverse of ex (and if it is defined in other ways, ex is defined as "the inverse of ln(x)"), I guess you would agree that any "elementary functional form" that has an inverse can be inverted into "elementary functional form".