Assignment 13 – Plot functions using abstract methods
(Plot functions using abstract methods) Write an abstract class that draws the diagram for a function. The class is defined as follows:
Test the class with the following functions:
a. f(x) = x2;
b. f(x) = sin(x);
c. f(x) = cos(x);
d. f(x) = tan(x);
e. f(x) = cos(x) + 5sin(x);
f. f(x) = 5cos(x) + sin(x);
g. f(x) = log(x) + x2;
For each function, create a class that extends the AbstractDrawFunction class and implement the f method. Figure below displays the drawing for the first three functions.
Mike. J. Thompson wrote:What is it you don't get?
You've been told to implement classes that evaluate those mathematical functions. Each of those classes must inherit from the class supplied by your tutor, and implement the abstract method f(...).
Ok I know I have to draw lines on a x and y grid but I'm really not sure how. we just went over abstract methods yesterday and we never went over graphics so I still don't fully understand abstract methods and how to draw on in a swing component.
A class with at least one abstract method must be abstract. An abstract class can't be instantiated.
Any class extending abstract class must either
 be abstract itself
 provide implementation for all abstract methods.
So, you have to make a subclass of AbstractDrawFunction class and then write method double f(double x) with actual body.
So, you have to draw sin(x). So just write a method that returns a sine of a number(Math.sin(double)  but you might want to scale it a little).
Then you should write somethig in method paintComponent(Graphics g). This method is called when the component is drawn.
As it is in your abstract class it should contain general code for plotting any of your functions.
What information do you have available inside this method?
You have a Polygon and Graphic.
Graphic is a class with many methods that can draw and paint things on components. If only it contained a method that could draw polygons.
A quick look at the API and voilà! It does have one.
It is drawPolygon(Polygon p).
But there is a little problem with that one. It connects the last points with the first one.
So the graph looks like this:
But wait! There is another method with similiar name that will not connect the last point to the first one! Unfortunately it doesn't take an instance of Polygon, but it takes something you can get from the Polygon.
Can you find it? Take a look here.
Pawel Pawlowicz wrote:Abstract method is a really simple thing. It's just a method without an implementation.
A class with at least one abstract method must be abstract. An abstract class can't be instantiated.
Any class extending abstract class must either
 be abstract itself
 provide implementation for all abstract methods.
So, you have to make a subclass of AbstractDrawFunction class and then write method double f(double x) with actual body.
So, you have to draw sin(x). So just write a method that returns a sine of a number(Math.sin(double)  but you might want to scale it a little).
Then you should write somethig in method paintComponent(Graphics g). This method is called when the component is drawn.
As it is in your abstract class it should contain general code for plotting any of your functions.
What information do you have available inside this method?
You have a Polygon and Graphic.
Graphic is a class with many methods that can draw and paint things on components. If only it contained a method that could draw polygons.
A quick look at the API and voilà! It does have one.
It is drawPolygon(Polygon p).
But there is a little problem with that one. It connects the last points with the first one.
So the graph looks like this:
But wait! There is another method with similiar name that will not connect the last point to the first one! Unfortunately it doesn't take an instance of Polygon, but it takes something you can get from the Polygon.
Can you find it? Take a look here.
ok ok this is what I got out of what you told me also
The classes you write should only need one method, f(double d). That method will calculate the function. name each of your classes after the function it implements.
Also, there is a method in the class your teacher provided that you need to add the implementation for. This method needs to draw the polygon, and you have already been given strong hints how to do that.
Mike. J. Thompson wrote:What isn't it doing right? Is there an error? Does it just not look the way you expected?
exactly some of them don't look the like the ones on google I never toke trigonometry
graph sin
https://www.google.com/search?espv=210&gs_ivs=1&q=trigonometry#q=graph+sin
graph cos
https://www.google.com/search?espv=210&gs_ivs=1&q=trigonometry#q=graph+cos
graph x^2
https://www.google.com/search?espv=210&gs_ivs=1&q=trigonometry#q=graph+x%5E2
graph tan
https://www.google.com/search?espv=210&gs_ivs=1&q=trigonometry#q=graph+tan
graph cos (x)+ 5sin(x)
https://www.google.com/search?espv=210&gs_ivs=1&q=trigonometry#q=graph+cos+(x)%2B+5sin(x)
graph 5cos (x)+ sin(x)
https://www.google.com/search?espv=210&gs_ivs=1&q=trigonometry#q=graph+5cos+(x)%2B+sin(x)
graph log
https://www.google.com/search?espv=210&gs_ivs=1&q=trigonometry#q=graph+log+
Buda young wrote:exactly some of them don't look the like the ones on google I never toke trigonometry
So, what DO they look like? They could be a lot flatter or more pronounced depending on the scales you're using.
Do you actually know that they're wrong, or do you just suspect it? I presume you're not getting errors because you haven't answered Mike's 2nd question with a "yes".
But primarily, I think your basic problem is that you've written far too much code without testing it.
Back up. Take one function (I'd suggest sin, because it's probably the most basic one), and test THAT. And don't even think about writing code for another one until you KNOW that it works. Every time.
HIH
Winston
PS: I broke up a couple of your code lines because they are far too long, and it makes your thread difficult to read. Please read the link. Thanks.
"Leadership is nature's way of removing morons from the productive flow"  Dogbert
Articles by Winston can be found here
Do you know what radians are and how they relate to degrees?
Look at the values you're returning in your f() methods and ask yourself why are are returning what you are, and whether that meets the requirements.
And as Winston said, do this one function at a time until you get it right.
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