Editing Pointing device (section)

== Control-Display Gain ==
The Control-Display Gain (or CD gain) describes the proportion between movements in the control space to the movements in the display space. For example, a hardware mouse moves in another speed or distance than the cursor on the screen. Even if these movements take place in two different spaces, the units for measurement have to be the same in order to be meaningful (e.g. meters instead of pixels). The CD gain refers to the scale factor of these two movements:
: <math>CD gain = V_{Display}/ V_{Control}</math>
The CD gain settings can be adjusted in most cases. However, a compromise has to be found: with high gains it is easier to approach a distant target, with low gains this takes longer. High gains hinder the selection of targets, whereas low gains facilitate this process.<ref>{{cite journal | last1=Meyer | first1=David E. | last2=Abrams | first2=Richard A. | last3=Kornblum | first3=Sylvan | last4=Wright | first4=Charles E. | last5=Keith Smith | first5=J. E. | title=Optimality in human motor performance: Ideal control of rapid aimed movements. | journal=Psychological Review | volume=95 | issue=3 | date=1988 | issn=1939-1471 | doi=10.1037/0033-295X.95.3.340 | pages=340–370| pmid=3406245 | s2cid=10474704 }}</ref> The [[Microsoft Windows|Microsoft]], [[Apple OS X|macOS]] and [[Xorg|X]] window systems have implemented mechanisms which adapt the CD gain to the user's needs. e.g. the CD gain increases when the user's movement velocity increases<ref>{{cite conference | last1=Casiez | first1=Géry | last2=Roussel | first2=Nicolas | title=No more bricolage!: methods and tools to characterize, replicate and compare pointing transfer functions | publisher=ACM | date=2011-10-16 | page= | isbn=978-1-4503-0716-1 | doi=10.1145/2047196.2047276 | pages=603–614}}</ref> (historically referred to as "mouse acceleration").