Where does vector collide?

In linear algebra a vector is an element of a vector space: an object that can be added to another of its kind and scaled by a number, with the familiar arrow (a quantity carrying both magnitude and direction) as the special case in the plane or in space. Strang's Introduction to Linear Algebra builds the subject from this idea, treating a vector as a list of numbers on which addition and scalar multiplication obey fixed axioms. The referent is a mathematical object, and its unit is whatever the space measures, whether metres, newtons, or nothing at all. What marks this meaning is that a vector is defined by how it combines with others, not by what it physically is; a force and a list of exam scores are both vectors when they satisfy the axioms.[1]

Unit

A mathematical object obeying the vector-space axioms

Recovery means

Not applicable

Measured by

Represented as coordinates in a chosen basis, with magnitude given by a norm

In epidemiology a vector is a living organism, most often a blood-feeding arthropod such as a mosquito, tick, or sandfly, that carries a pathogen from one host to another and so transmits an infectious disease. Wilson and colleagues, reviewing vector control for PLoS Neglected Tropical Diseases, treat the vector as the transmitting agent whose biology and behaviour decide how malaria, dengue, or leishmaniasis spread, and whose control breaks the chain of transmission. The referent is an organism, not a mathematical object, and the unit is a species or a population of insects. Here the word names the thing that carries a pathogen, which shares nothing with an element of a vector space beyond the Latin root for a carrier.[2]

Unit

A species or population of transmitting organisms

Recovery means

Not applicable

Measured by

Counted by species and abundance, and summarised by vectorial capacity

In computer science a vector is a data structure: a dynamically resizable array that stores a sequence of elements in contiguous memory and grows as items are appended. Stroustrup's The C++ Programming Language defines the standard-library vector as exactly this container, giving fast indexed access and automatic reallocation when the sequence outgrows its storage. The referent is a structure in a running program, and its unit is a container holding some number of elements. The name echoes the mathematical vector, and a fixed-length one can hold coordinates, but the construct is a storage mechanism with no notion of magnitude, direction, or the vector-space axioms; growing and indexing are what define it.[3]

Unit

A resizable container of elements in memory

Recovery means

Not applicable

Measured by

Described by its size, capacity, and access-time complexity