Proportsionaalne

Proportsionaalne is an Estonian adjective meaning proportional. In mathematics and science, proportsionaalne describes a relationship in which one quantity changes in direct proportion to another.

If y is proportional to x, there exists a non-zero constant k (the constant of proportionality) such that y = kx. In this case the ratio y/x remains constant for all valid x. Direct proportionality is used to model linear relationships that pass through the origin in Cartesian coordinates. If k > 0, y increases as x increases; if k < 0, y decreases as x increases.

Examples: Doubling x doubles y when y = 3x; more generally, the total cost C of buying x items at a fixed price p per item is C = p x; here C is proportional to x with k = p.

Distinctions: Proportsionaalne is contrasted with inverse proportionality, where y is proportional to 1/x and the product xy is constant rather than the ratio y/x.

In everyday language, proportsionaalne can describe other direct scaling relationships, such as data that scales linearly with time under a constant rate or physical laws with constant coefficients.

Origin and usage: The term stems from the broader concept of proportion and has been adopted into Estonian mathematics and science terminology to express a direct proportional relationship. Related terms include proportionality constant and linear relationship.