# Parameter

#### Noun

- (crystallography) The ratio of the three crystallographic axes which determines the position of any plane.
- (programming) An input variable of a procedure definition, that gets an actual value (argument) at execution time (formal parameter).
"Roughly, a tuple of arguments could be thought of as a vector, whereas a tuple of

**parameters**could be thought of as a covector (i.e., linear functional). When a function is called, a**parameter**tuple becomes "bound" to an argument tuple, allowing the function instance itself to be computed to yield a return value. This would be roughly analogous to applying a covector to a vector (by taking their dot product (or, rather, matrix-product of row vector and column vector)) to obtain a s" - (geometry) In the ellipse and hyperbola, a third proportional to any diameter and its conjugate, or in the parabola, to any abscissa and the corresponding ordinate.
"The

**parameter**of the principal axis of a conic section is called the latus rectum." - (mathematics, physics) A variable kept constant during an experiment, calculation or similar.
- A characteristic or feature that distinguishes something from others.
- (crystallography) The fundamental axial ratio for a given species.
- (programming) An actual value given to such a formal parameter (argument or actual parameter).