Definition:Proportion/Constant of Proportion

Definition

Let the two real variables $x$ and $y$ be proportional:

$\forall x, y \in \R: x \propto y \iff \exists k \in \R, k \ne 0: x = k y$

The constant $k$ is known as the constant of proportion.

Also known as

The constant of proportion is also known nowadays by the less elegant and more cumbersome constant of proportionality.

Some sources use proportionality constant.

Also see

• Results about constants of proportion can be found here.

Sources

• 1966: Isaac Asimov: Understanding Physics ... (previous) ... (next): $\text {I}$: Motion, Sound and Heat: Chapter $2$: Falling Bodies: Free Fall
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): variation: 1. (mutual variation)
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): constant of proportionality
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): variation: 1. (mutual variation)
• 2014: Christopher Clapham and James Nicholson: The Concise Oxford Dictionary of Mathematics (5th ed.) ... (previous) ... (next): proportion