Kubiskt

Kubiskt is a Swedish adjective meaning cubic, used in mathematics and related fields to describe objects of the third degree. In standard English mathematical terminology, the equivalent term is cubic.

In algebra, a kubisk funktion (cubic function) is any function of the form f(x) = ax^3 + bx^2 + cx + d with a ≠ 0. Such functions have up to three real roots; depending on the discriminant there may be one real and two complex roots. The cubic equation ax^3 + bx^2 + cx + d = 0 can be solved by Cardano's formula, though the expressions are more involved than for quadratics.

In geometry and computer graphics, kubiska kurvor (cubic curves) include cubic Bézier curves, defined by four control points and used to model smooth curves in vector graphics. Cubic splines are piecewise cubic polynomials used for smooth interpolation between data points; they preserve continuity up to the second derivative.

In algebraic geometry, cubical concepts appear in cubic curves and cubic surfaces defined by equations of degree three; classic examples include elliptic curves, which have the general form y^2 = x^3 + ax + b over a field.

Etymology and usage: kubiskt derives from Latin cubicus via Swedish. In English-language texts the term cubic is standard.