NHoldFirst is an attribute which specifies that the first argument to a function should not be affected by N.
NMaximize[f, x] maximizes f numerically with respect to x.NMaximize[f, {x, y, ...}] maximizes f numerically with respect to x, y, .... NMaximize[{f, cons}, {x, y, ...}] ...
NMinimize[f, x] minimizes f numerically with respect to x.NMinimize[f, {x, y, ...}] minimizes f numerically with respect to x, y, .... NMinimize[{f, cons}, {x, y, ...}] ...
NoncentralChiSquareDistribution[\[Nu], \[Lambda]] represents a noncentral \[Chi]^2 distribution with \[Nu] degrees of freedom and noncentrality parameter \[Lambda].
NumberFieldIntegralBasis[a] gives an integral basis for the field \[DoubleStruckCapitalQ][a] generated by the algebraic number a.
Opener
(Built-in Mathematica Symbol) Opener[x] represents an opener with setting x, displayed as OpenerBox[True] when x is True and OpenerBox[False] when x is False. Opener[Dynamic[x]] takes the setting to be ...
OpenWrite["file"] opens a file to write output to it, and returns an OutputStream object. OpenWrite[] opens a new file in the default area for temporary files on your ...
ParallelProduct[expr, {i, i_max}] evaluates the product \[Product]i = 1 i_max expr in parallel.ParallelProduct[expr, {i, i_min, i_max}] starts with i = ...
Pi
(Built-in Mathematica Symbol) Pi is \[Pi], with numerical value \[TildeEqual] 3.14159.
QPolyGamma[z, q] gives the q-digamma function \[Psi]_q (z).QPolyGamma[n, z, q] gives the n\[Null]^th derivative of the q-digamma function \[Psi]_q^(n)(z).