mathematics

The Simple Function Point method

The Simple Function Point method is a mathematics 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 The Simple Function Point method rather than just read about it. In short: The Simple Function Point (SFP) method is a lightweight Functional Measurement Method. The Simple Function Point method was designed by Roberto Meli in 2010 to be compliant with the ISO14143-1 standard and compatible with the International Function Points User Group (IFPUG) Function Point Analysis (FPA) method.

Key takeaways

The Simple Function Point method belongs to mathematics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect The Simple Function Point method to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of The Simple Function Point method from memory before moving on to harder problems.

Reference excerpt

The Simple Function Point (SFP) method is a lightweight Functional Measurement Method. The Simple Function Point method was designed by Roberto Meli in 2010 to be compliant with the ISO14143-1 standard and compatible with the International Function Points User Group (IFPUG) Function Point Analysis (FPA) method. The original method (SiFP) was presented for the first time in a public conference in Rome (SMEF2011) The method was subsequently described in a manual produced by the Simple Function Point Association: the Simple Function Point Functional Size Measurement Method Reference Manual, available under the Creatives Commons Attribution-NoDerivatives 4.0 International Public License.

Adoption by IFPUG In 2019, the Simple Function Points Method was acquired by the IFPUG, to provide its user community with a simplified Function Point counting method, to make functional size measurement easier yet reliable in the early stages of software projects. The short name became SFP. The SPM (Simple Function Point Practices Manual) was published by IFPUG in late 2021.

Basic concept When the SFP method was proposed, the most widely used software functional size measurement method was IFPUG FPA. However, IFPUG FPA had (and still has) a few shortcomings:

It is not easy to apply. It requires certified personnel, and the productivity of measurement is relatively low (between 400 and 600 Function Points per day, according to Capers Jones, between 200 and 300 Function Points per day according to experts from Total Metrics ). The measurement is partly subjective, since some of its measurement rules have to be suitably interpreted by the person who performs the measurement. The diffusion of the method in the software development community is quite limited. To overcome at least some of these problems, the SFP method was defined to provide the following characteristics:

Easy to apply; Less subject to interpretation, being based on quite straightforward definitions; Easy to learn: specifically, people familiar with IFPUG FPA could learn SFP very quickly with very little effort; Compatible with the IFPUG FPA; specifically S i z e [ U F P ] = S i z e [ S i F P ] {\displaystyle Size_{[UFP]}=Size_{[SiFP]}} , that is, a measure of size expressed in UFP should be equal to the measure expressed in SiFP (In this article we use “UFP” for unadjusted Function Point to designate the unit of measure defined by IFPUG FPA and SiFP the unit of measure defined by SFP). The sought characteristics were achieved as follows: IFPUG FPA requires that

logical data files and transactions are identified, logical data files are classified into Internal Logical Files (ILF) and External Interface Files (EIF), every transaction is classified as External Input (EI), External Output (EO), External Query (EQ), every ILF and EIF is weighted, based on its Record Element Types (RET) and Data Element Types (DET), every EI, EO and EQ is weighted, based on its File Types Referenced (FTR) and DET exchanged through the borders of the application being measured. Of these activities, SFP requires only the first two, i.e., the identification of logical data files and transactions. Activities 4) and 5) are the most time consuming, since they require that every data file and transaction is examined in detail: skipping these phases makes the SFP method both quicker and easier to apply than IFPUG FPA. In addition, most of the subjective interpretation is due to activities 4) and 5), and partly also to activity 3): skipping these activities makes the SFP method also less prone to subjective interpretation. The concepts used in the definition of SFP are a small subset of those used in the definition of IFPUG FPA, therefore learning SFP is easier than learning IFPUG FPA, and it is immediate for those who already know IFPUG FPA. In practice, only the concepts of logical data file and transaction have to be known. Finally, the weights assigned to data files and transactions make the size in SFP very close to the size expressed in Function Points, on average.

Definition The logical data files are named Logical Files (LF) in the SFP method. Similarly, transactions are named Elementary Process (EP). Unlike in IFPUG FPA, there is no classification or weighting of the Base Functional Components (BFC as defined in ISO14143-1 standard). The size of an EP is 4.6 SFP, while the size of a LF is 7.0 SFP. Therefore the size expressed in SFP is based on the number of data files (#LF) and the number of transactions (#EP). Belonging to the software application being measured:

S i z e [ S F P ] = 4.6 # E P + 7 # L F {\displaystyle Size_{[SFP]}=4.6\ \#EP+7\ \#LF}

Empirical evaluation of the SFP method Empirical studies have been carried out, aiming at

evaluating the convertibility of SFP and UFP measures comparing the SFP and UFP measures in supporting the estimation of software development effort

Convertibility between SFP and FPA measures

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with The Simple Function Point method

Start with the simplest possible case. Write down what The Simple Function Point method claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In mathematics, 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 The Simple Function Point method 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 The Simple Function Point method 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 The Simple Function Point method

In research: The Simple Function Point method appears in mathematics 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 The Simple Function Point method 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: The Simple Function Point method is common in secondary-school and first-year university syllabi. It links to neighbouring topics Software engineering costs, Software metrics, so understanding it makes those chapters shorter.
In everyday life: Look for The Simple Function Point method 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 The Simple Function Point method in 20 minutes

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

Frequently asked questions

What is The Simple Function Point method in simple terms?

Why does The Simple Function Point method matter?

Because it connects several mathematics 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 The Simple Function Point method?

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 The Simple Function Point method.