|Adj.||1.||idempotent - unchanged in value following multiplication by itself; "this matrix is idempotent"|
|1.||idempotent - A function f : D -> D is idempotent if|
f (f x) = f x for all x in D.
I.e. repeated applications have the same effect as one. This can be extended to functions of more than one argument, e.g. Boolean & has x & x = x. Any value in the image of an idempotent function is a fixed point of the function.
|2.||idempotent - This term can be used to describe C header files, which contain common definitions and declarations to be included by several source files. If a header file is ever included twice during the same compilation (perhaps due to nested #include files), compilation errors can result unless the header file has protected itself against multiple inclusion; a header file so protected is said to be idempotent.|
|3.||idempotent - The term can also be used to describe an initialisation subroutine that is arranged to perform some critical action exactly once, even if the routine is called several times.|