PolynomialLCM[poly_1, poly_2, ...] gives the least common multiple of the polynomials poly_i. PolynomialLCM[poly_1, poly_2, ..., Modulus -> p] evaluates the LCM modulo the ...
BarSpacing is an option to BarChart and related functions that controls the spacing between bars and groups of bars.
PlotRegion is an option for graphics functions that specifies what region of the final display area a plot should fill.
FactorList[poly] gives a list of the factors of a polynomial, together with their exponents.
MapIndexed[f, expr] applies f to the elements of expr, giving the part specification of each element as a second argument to f. MapIndexed[f, expr, levelspec] applies f to ...
Distribute[f[x_1, x_2, ...]] distributes f over Plus appearing in any of the x_i. Distribute[expr, g] distributes over g. Distribute[expr, g, f] performs the distribution ...
PrependTo[s, elem] prepends elem to the value of s, and resets s to the result.
Matrix inversion. Here is a simple 2×2 matrix. This gives the inverse of m. In producing this formula, Mathematica implicitly assumes that the determinant ad-bc is nonzero.
Streams
(Built-in Mathematica Symbol) Streams[] gives a list of all streams that are currently open. Streams["name"] lists only streams with the specified name.
Chop
(Built-in Mathematica Symbol) Chop[expr] replaces approximate real numbers in expr that are close to zero by the exact integer 0.