PseudoInverse[m] finds the pseudoinverse of a rectangular matrix.

QBinomial[n, m, q] gives the q-binomial coefficient (n; m)_q.

QPochhammer[a, q, n] gives the q-Pochhammer symbol (a; q) n.QPochhammer[a, q] gives the q-Pochhammer symbol (a; q) \[Infinity].QPochhammer[q] gives the q-Pochhammer symbol ...

QRDecomposition[m] yields the QR decomposition for a numerical matrix m. The result is a list {q, r}, where q is an orthogonal matrix and r is an upper-triangular matrix.

RandomChoice[{e_1, e_2, ...}] gives a pseudorandom choice of one of the e_i. RandomChoice[list, n] gives a list of n pseudorandom choices. RandomChoice[list, {n_1, n_2, ...}] ...

Rasterize[g] returns a rasterized graphic of g. Rasterize[g, elem] gives the element elem associated with the rasterized form of g.

Rationalize[x] converts an approximate number x to a nearby rational with small denominator. Rationalize[x, dx] yields the rational number with smallest denominator that lies ...

Rectangle[{x_min, y_min}, {x_max, y_max}] is a two-dimensional graphics primitive that represents a filled rectangle, oriented parallel to the axes. Rectangle[{x_min, y_min}] ...

Refine[expr, assum] gives the form of expr that would be obtained if symbols in it were replaced by explicit numerical expressions satisfying the assumptions assum. ...

ReliefImage[array] generates a relief image of an array of height values.