SeriesData[x, x_0, {a_0, a_1, ...}, n_min, n_max, den] represents a power series in the variable x about the point x_0. The a_i are the coefficients in the power series. The ...
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 ...
SessionTime[] gives the total number of seconds of real time that have elapsed since the beginning of your Mathematica session.
SetAccuracy[expr, a] yields a version of expr in which all numbers have been set to have accuracy a.
SetAlphaChannel[image] adds a fully opaque alpha channel to image.SetAlphaChannel[image, a] sets the opacity of all pixels to a.SetAlphaChannel[image, aimage] sets the alpha ...
lhs := rhs assigns rhs to be the delayed value of lhs. rhs is maintained in an unevaluated form. When lhs appears, it is replaced by rhs, evaluated afresh each time.
Set
(Built-in Mathematica Symbol) lhs = rhs evaluates rhs and assigns the result to be the value of lhs. From then on, lhs is replaced by rhs whenever it appears. {l_1, l_2, ...} = {r_1, r_2, ...} evaluates ...
SetOptions[s, name_1 -> value_1, name_2 -> value_2, ...] sets the specified default options for a symbol s. SetOptions[stream, ...] or SetOptions["name", ...] sets options ...
SetPrecision[expr, p] yields a version of expr in which all numbers have been set to have precision p.
SetSelectedNotebook[notebook] makes the specified notebook be the currently selected one in the front end.