InverseErf[s] gives the inverse error function obtained as the solution for z in s = erf(z).
KarhunenLoeveDecomposition[{a_1, a_2, ...}] gives the Karhunen\[Dash]Loeve transform {b_1, b_2, ...} of the numerical arrays {a_1, a_2, ...} and the transformation matrix m, ...
KatzCentrality[g, \[Alpha]] gives a list of Katz centralities for the vertices in the graph g and weight \[Alpha].KatzCentrality[g, \[Alpha], \[Beta]] gives a list of Katz ...
LayerSizeFunction is an option for TreePlot that gives a function to specify the relative height to allow for each layer.
Length
(Built-in Mathematica Symbol) Length[expr] gives the number of elements in expr.
LinkClose[link] closes an open MathLink connection.
LocalizeVariables is an option to Manipulate that determines whether the values of variables associated with controls should be localized.
LocatorRegion is an option for Locator that specifies where the locator object should by default be allowed to go when it is dragged.
MatchLocalNames is an option for Trace and related functions that specifies whether symbols such as x should match symbols with local names of the form x$nnn.
MatchQ
(Built-in Mathematica Symbol) MatchQ[expr, form] returns True if the pattern form matches expr, and returns False otherwise.