InverseErfc[s] gives the inverse complementary error function obtained as the solution for z in s = erfc(z).
InverseFunctions is an option for Solve and related functions that specifies whether inverse functions should be used.
LibraryFunctionLoad[lib, fun, argtype, rettype] loads Wolfram Library lib and makes the library function fun available in Mathematica.
MathieuC[a, q, z] gives the even Mathieu function with characteristic value a and parameter q.
MaxSteps is an option to functions like NDSolve that specifies the maximum number of steps to take in generating a result.
Modulus
(Built-in Mathematica Symbol) Modulus -> n is an option that can be given in certain algebraic functions to specify that integers should be treated modulo n.
O
(Built-in Mathematica Symbol) O[x]^n represents a term of order x^n. O[x]^n is generated to represent omitted higher-order terms in power series. O[x, x_0]^n represents a term of order (x - x_0) n.
ProgressIndicator[x] represents a progress indicator with setting x in the range 0 to 1. ProgressIndicator[Dynamic[x]] takes the setting to be the dynamically updated current ...
RadioButton[x, val] represents a radio button whose setting x is set to val when the button is clicked. RadioButton[x, val] is displayed as RadioButtonBox[0, {0}] when x is ...
RamanujanTauL[s] gives the Ramanujan tau Dirichlet L-function L(s).