In engineering design
, a function/means tree
(a.k.a. function-means tree
or F/M tree
) is a method for functional decomposition and concept generation. At the top level main functions are identified. Under each function, a means (or solution element) is attached. Alternative solution elements can also be attached. Each means is in turn decomposed into functions with means attached to each of them. A well elaborated function means tree span a design space where all concepts under consideration are represented. Requirements can be attached to functions.
In addition to the product level requirements, there might be requirements on sub functions that may be a consequence of means at a higher level. The function means tree is a tool that can aid in the creative par of the design process. It can also be a tool for mapping requirements to parts in a design. This requires that there is also a mapping between means and parts in the product architecture.