computer science

Rank (computer programming)

Rank (computer programming) is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Rank (computer programming) rather than just read about it. In short: In computer programming, rank with no further specifications is usually a synonym for (or refers to) "number of dimensions"; thus, a two-dimensional array has rank two, a three-dimensional array has rank three and so on. Strictly, no formal definition can be provided which applies to every programming language, since each of them has its own concepts, semantics and terminology; the term may not even be applicable or…

Key takeaways

Rank (computer programming) belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Rank (computer programming) to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Rank (computer programming) from memory before moving on to harder problems.

Reference excerpt

In computer programming, rank with no further specifications is usually a synonym for (or refers to) "number of dimensions"; thus, a two-dimensional array has rank two, a three-dimensional array has rank three and so on. Strictly, no formal definition can be provided which applies to every programming language, since each of them has its own concepts, semantics and terminology; the term may not even be applicable or, to the contrary, applied with a very specific meaning in the context of a given language. In the case of APL the notion applies to every operand; and dyads ("binary functions") have a left rank and a right rank. The box below instead shows how rank of a type and rank of an array expression could be defined (in a semi-formal style) for C++ and illustrates a simple way to calculate them at compile time.

Given the code above the rank of a type T can be calculated at compile time by

or the shorter form

Calculating the rank of an expression can be done using

See also Rank (linear algebra), for a definition of rank as applied to matrices Rank (J programming language), a concept of the same name in the J programming language

References

Worked examples

Example 1 — a first encounter with Rank (computer programming)

Start with the simplest possible case. Write down what Rank (computer programming) claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Rank (computer programming) before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Rank (computer programming) ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Rank (computer programming)

In research: Rank (computer programming) appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Rank (computer programming) in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Rank (computer programming) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arrays, Programming language topic stubs, Programming language topics, so understanding it makes those chapters shorter.
In everyday life: Look for Rank (computer programming) outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Rank (computer programming) in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Rank (computer programming) means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Rank (computer programming) out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Rank (computer programming) in simple terms?

Why does Rank (computer programming) matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Rank (computer programming)?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Rank (computer programming).