Retningavhengighet

Retningavhengighet, or directional dependence, is a property of a system or measurement where a quantity varies with the direction in which it is observed or measured. It is the opposite of isotropy, where the property is the same in all directions. The term is commonly used in Norwegian as a translation of anisotropy in scientific contexts.

Directionality can arise from underlying structure, such as crystal lattices, fiber orientation in composites, layered geological formations, or directional signaling in biological tissues. In physics, many materials display retningavhengighet in properties like electrical conductivity, magnetic permeability, optical refractive index, and elastic stiffness, which are often represented by tensors rather than simple scalars.

Measurement and modelling typically involve sampling across multiple directions and expressing the variation with direction through mathematical constructs such as second-order tensors or angular functions. In practice, the degree of anisotropy is quantified using eigenvalues, anisotropy indices, or diffusion tensor imaging in medical contexts.

Understanding retningavhengighet is important for accurate predictions and design, from engineering components and electronic devices to interpreting seismic data and imaging results. The concept also underpins methods to compensate for directional biases, such as BRDF correction in remote sensing or orientation-aware data analysis.

See also: anisotropy, tensor, diffusion tensor imaging, BRDF, directional statistics.