ZTransform[expr, n, z] gives the Z transform of expr. ZTransform[expr, {n_1, n_2, ...}, {z_1, z_2, ...}] gives the multidimensional Z transform of expr.
SeriesCoefficient[series, n] finds the coefficient of the n\[Null]\[Null]^th-order term in a power series in the form generated by Series. SeriesCoefficient[f, {x, x_0, n}] ...
Product
(Built-in Mathematica Symbol) Product[f, {i, i_max}] evaluates the product \[Product]i = 1 i_max f. Product[f, {i, i_min, i_max}] starts with i = i_min. Product[f, {i, i_min, i_max, di}] uses steps di. ...
LegendreQ[n, z] gives the Legendre function of the second kind Q_n (z). LegendreQ[n, m, z] gives the associated Legendre function of the second kind Q_n^m(z).
Series
(Built-in Mathematica Symbol) Series[f, {x, x_0, n}] generates a power series expansion for f about the point x = x_0 to order (x - x_0) n. Series[f, {x, x_0, n_x}, {y, y_0, n_y}, ...] successively finds ...
HermiteH[n, x] gives the Hermite polynomial H_n (x).
UnitStep[x] represents the unit step function, equal to 0 for x < 0 and 1 for x >= 0. UnitStep[x_1, x_2, ...] represents the multidimensional unit step function which is 1 ...
Sum
(Built-in Mathematica Symbol) Sum[f, {i, i_max}] evaluates the sum \[Sum]i = 1 i_max f. Sum[f, {i, i_min, i_max}] starts with i = i_min. Sum[f, {i, i_min, i_max, di}] uses steps d i. Sum[f, {i, {i_1, i_2, ...
DiscreteConvolve[f, g, n, m] gives the convolution with respect to n of the expressions f and g. DiscreteConvolve[f, g, {n_1, n_2, ...}, {m_1, m_2, ...}] gives the ...
DSolve
(Built-in Mathematica Symbol) DSolve[eqn, y, x] solves a differential equation for the function y, with independent variable x. DSolve[{eqn_1, eqn_2, ...}, {y_1, y_2, ...}, x] solves a list of ...