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Doesn't know and doesn't care

The plotting program doesn't know, and doesn't care how the interface method decides on the value to return for each value that it receives as an incomingparameter. The plotting program simply calls the methods to get the data, and then plots the returned values.

Computed "on the fly"

For example, the returned values could be computed and returned "on the fly," as was the case in the example program named Graph01Demo , which I explained in the module titled Plotting Engineering and Scientific Data using Java .

Returned from an array

On the other hand, the values could have been computed earlier and saved in an array. That is the case with all the programs that I will explain in thismodule.

From a disk file, a database, the internet, etc.

The returned values could be read from a disk file, obtained from a databaseon another computer, or obtained from any other source such as another computer on the Internet.

All that matters is that when the plotting program calls one of the five methods named f1 through f5 , passing a double value as a parameter, it expects to receive a double value in return, and it will plot the value that it receives.

The getNmbr method

The getNmbr method for the class named Dsp029 is shown in Listing 6 .

Listing 6. The getNmbr method.
public int getNmbr(){ //Return number of functions to// process. Must not exceed 5. return numberSinusoids;}//end getNmbr

This is a very simple method. It returns the value stored in the variable named numberSinusoids . This variable may contain the default value established by Listing 1 , or may contain the value read from the file named Dsp029.txt by the method named getParameters .

The method named f1

The code for the method named f1 is shown in Listing 7 .

Listing 7. The method named f1.
public double f1(double x){ int index = (int)Math.round(x);if(index<0 || index>data1.length-1){ return 0;}else{ return data1[index]; }//end else}//end function

Note that there is not a one-to-one correspondence between horizontal coordinate values and pixels on the screen. For example, it may sometimes benecessary to plot 90 values across an area of the screen containing 110 pixels. The plotting program must interpolate properly to deal with that issue.Therefore, the plotting program deals with horizontal coordinates as type double and then converts those coordinate values to integer pixel values when the timecomes to actually draw the material on the screen.

Round from double to int

The method named f1 receives an incoming horizontal coordinate value as type double . It rounds that value to the nearest value of type long and casts it to type int to determine the index value to use when retrieving the corresponding verticalvalue from the array object.

If the index value is outside the bounds of the array, the method simply returns a value of zero. Otherwise, it uses the index value to return the valuestored in the array object at that index.

The remaining interface methods

The remaining four interface methods are identical to the method named f1 , except that each method returns data values stored in a different array object. Therefore, I won't discuss those methods.

Questions & Answers

what is monopoli power
Adzaho Reply
the situation that prevails when economic forces balance so that economic variables neither increase nor decrease
Bombey
what is equilibrium
Kabir
what are the important of economic to accounting students with references
salihu Reply
Economics is important because it helps people understand how a variety of factors work with and against each other to control how resources such as labor and capital get used, and how inflation, supply, demand, interest rates and other factors determine how much you pay for goods and services.
Muhammad
explain the steps taken by the government in developing rural market?
Azeem Reply
contribution of Adam smith in economics
abel Reply
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AS
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Umarou
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AS
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Amir
what is the meaning of function in economics
Effah Reply
Pls, I need more explanation on price Elasticity of Supply
Isaac Reply
Is the degree to the degree of responsiveness of a change in quantity supplied of goods to a change in price
Afran
what is production
Humaira
Okay what is land mobile and land unmobile
scor
And what are the resources in land
scor
what is production
Humaira
the proces of using the services of labor and equipmnt together with other in puts to make goods and services availble
Bombey
Okay what is land mobile and land unmobile
scor
Discuss the short-term and long-term balance positions of the firm in the monopoly market?
Rabindranath Reply
hey
Soumya
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Mitiku
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Mitiku
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Soumya
through hard study and performing well than expected from you
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Soumya
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Mitiku
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Soumya
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Rabindranath
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Mitiku
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Momoh
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Isaac
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Afran
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Afran
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OLANIYI
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Lerato
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Umarou
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Humaira
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Liaqat
what is firms
Anteyi Reply
A firm is a business entity which engages in the production of goods and aimed at making profit.
Avuwada
What is autarky in Economics.
Avuwada
what is choice
Tia Reply
So how is the perfect competition different from others
Rev Reply
what is choice
Tia
please what type of commodity is 1.Beaf 2.Suagr 3.Bread
Alfred Reply
1
Naziru
what is the difference between short run and long run?
Ukpen Reply
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Anna
meaning? You guys need not to be playing here; if you don't know a question, leave it for he that knows.
Ukpen
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Ada
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Ukpen
This place is meant to be for serious educational matters n not playing ground so pls let's make it a serious place.
Docky
Is there an economics expert here?
Docky
Okay and I was being serous
Anna
The short run is a period of time in which the quantity of at least one inputs is fixed...
Anna
that is the answer that I found online and in my text book
Anna
Elacisity
salihu
Meaning of economics
Suraj Reply
It will creates rooms for an effective demands.
Chinedum Reply
different between production and supply
babsnof
Hii
Suraj
hlo
eshita
What is the economic?
Suraj
Economics is a science which study human behavior as a relationship between ends and scarce means which has an alternative use.
Mr
what is supply
babsnof
what is different between demand and supply
Debless Reply
Demand refers to the quantity of products that consumers are willing to purchase at various prices per time while Supply has to do with the quantity of products suppliers are willing to supply at various prices per time. find the difference in between
Saye
what is demand
Humaira
demand is a relationship btn the price of an item and the quantity demanded
Bombey
Difference between extinct and extici spicies
Amanpreet Reply
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Source:  OpenStax, Digital signal processing - dsp. OpenStax CNX. Jan 06, 2016 Download for free at https://legacy.cnx.org/content/col11642/1.38
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