DiscreteIndicator[x, x_1, {u_1, u_2, ...}] yields the discrete indicator function, equal to 1 if x = x_1 and 0 if x = u_i for any i.
Projection[u, v] finds the projection of the vector u onto the vector v.Projection[u, v, f] finds projections with respect to the inner product function f.
GaussianMatrix[r] gives a matrix that corresponds to a Gaussian kernel of radius r. GaussianMatrix[{r, \[Sigma]}] gives a matrix corresponding to a Gaussian kernel with ...
Norm
(Built-in Mathematica Symbol) Norm[expr] gives the norm of a number, vector or matrix. Norm[expr, p] gives the p-norm.
AxesOrigin is an option for graphics functions that specifies where any axes drawn should cross.
BitOr
(Built-in Mathematica Symbol) BitOr[n_1, n_2, ...] gives the bitwise OR of the integers n_i.
BitAnd
(Built-in Mathematica Symbol) BitAnd[n_1, n_2, ...] gives the bitwise AND of the integers n_i.
BitXor
(Built-in Mathematica Symbol) BitXor[n_1, n_2, ...] gives the bitwise XOR of the integers n_i.
Divisors[n] gives a list of the integers that divide n.
Implies
(Built-in Mathematica Symbol) Implies[p, q] represents the logical implication p \[DoubleRightArrow] q.