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There is no single universal meaning for the double dot operator (`..`). In Db2, it invokes a method; in the cited GTA3script grammar, it marks an inclusive character range. In continuum mechanics, double-dot symbols denote tensor contractions. The surrounding language or formula determines which meaning applies.
How to identify the meaning of `..`
Look at the syntax around the dots and identify the language or field. A value followed by `..` and a method name points to Db2; quoted characters on either side point to the GTA3script grammar notation; indexed tensors with a double-dot or colon between them point to continuum mechanics. These are distinct operations, not interchangeable definitions.
| Context | Typical notation | What it means | Result |
|---|---|---|---|
| Db2 structured types | subject..method(arguments) |
Invokes a method on the subject | The method’s return value |
| GTA3script grammar | 'A'..'Z' |
Inclusive range of characters | A set of grammar alternatives |
| Continuum mechanics | Indexed dyadics with `··` or `:` | Contracts tensor indices | A scalar in the cited dyadic examples |
What does the double dot operator mean in Db2?
In IBM Db2 11.1, the double-dot operator invokes a method on a value with a user-defined structured type. The subject expression comes first, followed by .., an unqualified method name, and optional arguments. The method must be defined for the subject’s static type or one of its supertypes. Db2 resolves the method using its name and the argument types. See IBM’s method invocation documentation.
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1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteFor example, IBM shows SELECT CIRCLE_COL..AREA() FROM RINGS, where AREA is a method defined for a CIRCLE structured type. A zero-argument method can be written with or without parentheses.
Db2 gives method invocation high precedence and associates chained calls from left to right. Thus a..b..c + x..y..z is grouped as ((a..b)..c) + ((x..y)..z).
Null handling is also specific to Db2: calling a system-generated mutator on a null subject raises an error (SQLSTATE 2202D). Other method calls on null subjects are not executed and yield null.
Rank #2
What does `..` mean in the GTA3script grammar?
The GTA3script specification uses a variation of EBNF, a notation for describing language syntax. In that grammar, two dots between terminal characters mark an inclusive range. For example, digit := '0'..'9' ; means the grammar allows the characters from 0 through 9. It describes grammar alternatives, not a runtime arithmetic range operation. The definition appears in the GTA3script specification.
What does double dot mean in tensor notation?
In continuum mechanics, double-dot notation can denote a contraction of two dyadic tensors. The cited excerpt from Essentials of Continuum Framework distinguishes a horizontal contraction, written `··`, from a vertical contraction, written `:`:
Rank #3
- Horizontal:
Aij ·· Bij = AijBji - Vertical:
Aij : Bij = AijBij
Both produce a scalar in these dyadic examples, but the index arrangement differs. Consequently, the results need not match when the dyadics are nonsymmetric. The horizontal contraction is zero when one dyadic is symmetric and the other is antisymmetric. The excerpt defines the dyadic norm using the vertical contraction. Because notation can vary, keep the author’s symbols and index convention in view when interpreting a formula.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What context should you provide to get the right definition?
If you are asking about a specific instance, include the language or field and a short surrounding expression. The same two periods can signal method invocation or a grammar range, while tensor formulas use related-looking glyphs with index conventions. Without that context, assigning one meaning to “double dot operator” would be misleading.
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