# delta

n. 1. [techspeak] A quantitative change, especially a small
or incremental one (this use is general in physics and
engineering). "I just doubled the speed of my program!" "What
was the delta on program size?" "About 30 percent." (He
doubled the speed of his program, but increased its size by only 30
percent.) 2. [UNIX] A

diff, especially a

diff stored
under the set of version-control tools called SCCS (Source Code
Control System) or RCS (Revision Control System). 3. n. A small
quantity, but not as small as

epsilon. The jargon usage of

delta and

epsilon stems from the traditional use of these
letters in mathematics for very small numerical quantities,
particularly in `epsilon-delta' proofs in limit theory (as in the
differential calculus). The term

delta is often used, once

epsilon has been mentioned, to mean a quantity that is
slightly bigger than

epsilon but still very small. "The cost
isn't epsilon, but it's delta" means that the cost isn't totally
negligible, but it is nevertheless very small. Common
constructions include `within delta of ---', `within epsilon of
---' that is, close to and even closer to.