computer science

ScaLAPACK

ScaLAPACK 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 ScaLAPACK rather than just read about it. In short: The ScaLAPACK (or Scalable LAPACK) library includes a subset of LAPACK routines redesigned for distributed memory MIMD parallel computers. It is currently written in a Single-Program-Multiple-Data style using explicit message passing for interprocessor communication.

Key takeaways

ScaLAPACK 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 ScaLAPACK to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of ScaLAPACK from memory before moving on to harder problems.

Reference excerpt

The ScaLAPACK (or Scalable LAPACK) library includes a subset of LAPACK routines redesigned for distributed memory MIMD parallel computers. It is currently written in a Single-Program-Multiple-Data style using explicit message passing for interprocessor communication. It assumes matrices are laid out in a two-dimensional block cyclic decomposition. ScaLAPACK is designed for heterogeneous computing and is portable on any computer that supports MPI or PVM. ScaLAPACK depends on PBLAS operations in the same way LAPACK depends on BLAS. As of version 2.0, the code base directly includes PBLAS and BLACS and has dropped support for PVM. After two decades of operation, a new library was created to replace ScaLAPACK, which was not suitable for modern accelerated architectures. Slate is written in C++ and was designed primarily to serve as a dense linear algebra library to the United States Department of Energy and to the high-performance computing community at large.

Examples Programming with Big Data in R fully utilizes ScaLAPACK and two-dimensional block cyclic decomposition for Big Data statistical analysis which is an extension to R.

References

External links The ScaLAPACK Project on Netlib.org

Worked examples

Example 1 — a first encounter with ScaLAPACK

Start with the simplest possible case. Write down what ScaLAPACK 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 ScaLAPACK 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 ScaLAPACK 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 ScaLAPACK

In research: ScaLAPACK 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 ScaLAPACK 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: ScaLAPACK is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer libraries, Computer library stubs, Numerical software, so understanding it makes those chapters shorter.
In everyday life: Look for ScaLAPACK 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 ScaLAPACK in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what ScaLAPACK 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 ScaLAPACK out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is ScaLAPACK in simple terms?

Why does ScaLAPACK 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 ScaLAPACK?

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 ScaLAPACK.