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  • xMin and xMax - The values of the left and right ends of all horizontal axes.
  • yMin and yMax - The values of the bottom and top of the vertical axis in each plotting area. (Note that the different plotting areas are identified by alternating white and gray backgrounds.)
  • xTicInt - The distance between tic marks on the x-axis.
  • yTicInt - The distance between tic marks on the y-axis.
  • xCalcInc - The distance between the points on the x-axis where values for y are computed. (Unless your data-generator program is taking too long to run, you should probably leave this set to 1.0 in order to get the bestquality plots.)

The labels on the axes

Each x-axis has a label at the left end and the right end. Similarly, each y-axis has a label at the bottom and the top. These labels represent the valuesat the extreme ends of the axes. For example in Figure 2 , the label 800 appears at the right end of each x-axis. This is value of the x-axis where the axisintersects the border of the frame.

Keep the pixels in mind

When adjusting the plotting parameters, keep in mind that the total width of each of the plotting areas is slightly less than 400 pixels.

(You can easily increase this to full screen width by changing one value in the Graph01 program and recompiling the program. However, I had to keep it narrow in order to publish the imagesin this publication format.)

While you can theoretically make the horizontal expanse of the x-axes as wide as you wish, because of the pixel limitation, you cannot see details thatrequire a resolution greater than the number of pixels along the x-axis. (This might be a good reason for you to modifythe Graph01 program as described above).

The interface named GraphIntfc01

Regardless of the simplicity or complexity of your data-generator program, there are only two requirements for your program to operate successfully with theplotting program named Graph01 :

  1. It must implement the interface named GraphIntfc01 .
  2. It must have a constructor that doesn't require any parameters (the default constructor will satisfy that requirement if you don't need anotherconstructor) .

Implementing graphintfc01

All that is required to implement the interface is to define a class that provides a concrete definition for each of the six methods declared in Listing 1 .

Listing 1. Source code for GraphIntfc01.java.
public interface GraphIntfc01{ public int getNmbr();public double f1(double x); public double f2(double x);public double f3(double x); public double f4(double x);public double f5(double x); }//end GraphIntfc01

The method named getnmbr

On several occasions in this module, I have stated that the plotting program can plot up to five functions. However, it doesn't have to plot allfive functions. The plotting program can be used (without modification) to plot any number of functions from one to five.

The method named getNmbr , that you must define in your data-generator program, must return an integer value between 1 and 5 that specifies the number of functions to be plotted. Theplotting program uses that value to divide the total plotting surface into the specified number of plotting areas, and plots each of the functions named f1 through fn in one of those plotting areas.

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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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