Inverse (mathematics)

Inversion (or finding the inverse) is an idea from mathematics, which is about finding a number, function or mathematical structure which is different from the current one, but which has similar properties.  The simplest case of this is negation: Given a positive number, find the negative number which has the same value, except for the sign. 

Inversion can refer to the following concepts:
The inverse element for addition or for multiplication.
An inverse function
Inverse (logic)
The inversion of an Invertible matrix
The Fourier inversion theorem states that sometimes, it is possible to reconstruct the original function, after a Fourier transform
In Set theory, the complement will return all elements not in the set.
Inversive geometry studies the properties of a shape that are preserved after geometrical inversion.