FourQuadrant

Fourquadrant, or four-quadrant, is a term used to describe systems, devices, or analyses that consider or operate over four distinct regions defined by two perpendicular axes. The concept appears in mathematics, electronics, engineering, and data analysis, among other fields. The exact meaning depends on the context, but common threads include symmetry across axes and the ability to handle opposite signs or directions.

In mathematics, the Cartesian plane is divided into four quadrants by the x- and y-axes. Quadrant I contains points with x>0 and y>0; Quadrant II, x<0, y>0; Quadrant III, x<0, y<0; Quadrant IV, x>0, y<0. This partition supports qualitative reasoning about sign, quadrant-based classification, and complex-number representation phases.

In electronics and control engineering, four-quadrant refers to devices or systems that can handle signed signals in both input and output, enabling operation in four combinations of direction and magnitude. Examples include four-quadrant analog multipliers and four-quadrant power converters used in motor drives and regenerative braking, where the system must function in motoring and braking modes with bidirectional power flow.

In data analysis, quadrant analysis partitions a two-variable space into four sectors defined by two threshold lines, aiding interpretation of relationships or performance relative to reference levels. The technique is used in quality control, risk assessment, and strategic planning to categorize observations or products.

The term is often spelled with a hyphen or as two words; in some contexts it also appears as four-quadrant or four quadrant. It serves as a generic descriptor rather than a specific product name, and its precise definition reflects the domain of application.