delta

1. 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). See changemanagement.

3. 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".

[Jargon File]

(2000-08-02)