# 3.4 Java3003: drawing graphs with turtles and pixels  (Page 7/13)

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There is nothing new in Listing 8 . You should be able to correlate the code in Listing 8 and the drawing parameters in Listing 7 with the steps presented earlier to understand how the program named Parabola01 produces the output image shown in Figure 6 .

## A cubic

The program named Cubic01 shown in Listing 17 produces the graphic output shown in Figure 9

Figure 9. Graphic output from the program named Cubic01.

About the only thing that is different between the program named Parabola01 and the program named Cubic01 is the methodnamed function . In the program named Parabola01 , the method computes and returns the square of the incoming x-value. In theprogram named Cubic01 , the method computes and returns the cube of the incoming x-value. Just about everything that was said about Parabola01 also applies to Cubic01 .

## A circle

There are several ways to graph all of the functions discussed in this lesson. The previous sections have illustrated only one way -- using a turtle tograph the function. I will illustrate the following two ways to graph a circle in this section and will compare some of the advantages and disadvantages of each approach :

• Using a turtle to graph the function
• Accessing and setting pixel colors

## First approach

The first approach that I will present and explain uses a turtle to graph a circle. This program is very similar to the program named Parabola01 , but there are a few differences. I will explain those differences.

The program named Circle01 shown in Listing 18 produces the graphic output shown in Figure 10 .

Figure 10. Graphic output from the program named Circle01.

The first difference that is worthy of note is shown by the lines of code involving the variable named rVal in Listing 9 .

Listing 9 . The variable named rVal. ```double rVal = 0.6;//radius relative to 1.0 double yVal = 0;int row = 0; int col = 0;double xVal = -rVal; double xInc = 2*rVal/100;turtle.setPenColor(Color.BLUE);```

The variable named rVal is used to specify the radius of the circle relative to a value of 1.0 as declared and initialized in Listing 9 .

In the previous sections, we have evaluated our equation for a set of 101 x values ranging from -1.0 to +1.0. For the case of the circle, we will evaluatethe equation for a set of 101 x values ranging from -rVal to +rVal . ( There is no point in evaluating the equation outside of the circle.)

The code in Listing 9 declares and initializes the variable named rVal . Further down, the code sets the initial value for xVal to -rVal . Below that, the code sets the x-increment ( xInc ) to the diameter of the circle divided by 100. This will cause the equation for the circle to beevaluated at 101 points from left to right across the circle shown in Figure 10 .

## The method named function for Circle01

The method named function is shown in Listing 10 .

This method evaluates and returns the y-value for each incoming x-value for a circle with no offset, centered at the origin.The method evaluates the standard equation for a circle given by

`radius*radius = x*x + y*y`

Note that unlike the function method for Parabola01 and Cubic01 , this method requires two incoming parameters: the radius and the current x-value.

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
how did you get the value of 2000N.What calculations are needed to arrive at it
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