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If you did it all correctly, your program should calculate the square root. (For reasons that will become apparent later, I will refer to the code that you inserted as in-line code.)

Oops, need to do it all over again

Suppose that further on in your program you discover that you need to calculate the square root of another number. And later, you discover that youneed to calculate the square root of still another number. Obviously, with a few changes, you could copy your original code and insert it as in-line code at each location in your program where you need to calculate the square root ofa number.

Is there a better way?

However, after doing this a few times, you might start asking if there is a better way. The answer is "yes, there is a better way."

A programming module provides a better way

The better way is to create a separate program module that has the ability to calculate the square root and to make that module available for use as a helperto your main program each time your main program needs to calculate a square root. In some programming languages, this separate program module is oftencalled a function or a method. In scratch 2.0, it doesn't have a specific name. I will refer to it as a custom block . You create a custom block in Scratch 2.0 by selecting the More Blocks toolbox shown in Image A .

Image a. the more blocks toolbox.

Missing image.
Image A. The More Blocks toolbox.

Library functions

Most modern programming languages provide a large number of pre-written functions that are already available for your use.

In addition to the library functions that are already available, if you need a function to perform some operation and there is no library function alreadyavailable to perform that operation, you can write your own function.

A similar library for mathematical functions exists in Scratch 2.0. The library is accessed using the bottom block in the Operators toolbox with the selection sqrt shown in Image B .

Image b. access to scratch 2.0 math functions.

Missing image.
Image B. Access to Scratch 2.0 math functions.

Image C shows the different mathematical function selections that are available in the pull down list of the block. (Note that the fourth one from the top is the sqrt function.)

Image c. mathematical functions available in scratch 2.0.

Missing image.
Image C. Mathematical functions available in Scratch 2.0.

Passing parameters

Make the function general

Normally, in the case of designing and writing a function such as one that can calculate the square root of a number, it is desirable to write it in such away that it can calculate the square root of any number (as opposed to only one specific number) . This is accomplished through the use of something called parameters.

Pass me the number please

The process of causing a function to be executed is commonly referred to as calling the function.

When your program calls the square-root function, it will need to tell the function the value of the number for which the square root is needed. Ingeneral, many functions will require that you provide certain kinds of information when you call them. The code in the function needs this informationto be able to accomplish its purpose.

Questions & Answers

what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
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Source:  OpenStax, Teaching beginners to code. OpenStax CNX. May 27, 2013 Download for free at http://cnx.org/content/col11498/1.20
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