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4.7 Java1491-2d fourier transforms using java, part 2  (Page 9/21)

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Listing 6. Create and save the test surface.
int rows = 41; int cols = 41;double[][]spatialData = getSpatialData(switchCase,rows,cols);

I will discuss the method named getSpatialData in detail later. For now, just assume that the 2D array object referred to by spatialData contains the test surface when this method returns.

Display the test surface

Listing 7 instantiates an object of the class named ImgMod29 to display the test surface in the display format indicated by the value of displayType .

Listing 7. Display the test surface.
new ImgMod29(spatialData,3,false,displayType);

The value of false in the third parameter indicates that the axes should not be displayed.

(See the module titled Plotting 3D Surfaces using Java for an explanation of the second parameter. Basically, this parameter is used to control the overallsize of the plot on the screen.)

An example test surface plot

The top-left image in Figure 4 is an example of the output produced by the code in Listing 7 for a displayType value of 0.

( Figure 4 shows the grayscale format. See the module titled Plotting 3D Surfaces using Java for an explanation of the three available non-logarithmic display formats.)

Figure 4. An example test surface plot.
missing image

Figure 4 shows the results for a test surface switchCase value of 2. I will discuss the particulars of this case in detail later.

Perform the forward Fourier transform

Listing 8 performs the forward Fourier transform to transform the test surface into the wavenumber domain.

Listing 8. Perform the forward Fourier transform.
double[][]realSpect = //Real part new double[rows][cols];double[][]imagSpect = //Imaginary part new double[rows][cols];double[][]amplitudeSpect = //Amplitude new double[rows][cols];ImgMod30.xform2D(spatialData,realSpect, imagSpect,amplitudeSpect);

Prepare array objects to receive the transform results

Listing 8 begins by preparing some array objects to receive the transform results. The forward transform receives an incoming surface array and returnsthe real and imaginary parts of the complex wavenumber spectrum along with the amplitude spectrum by populating three array objects passed as parameters to themethod.

Perform the forward transform

Then Listing 8 calls the static xform2D method of the ImgMod30 class to perform the forward transform, returning the results by way of the parameters to the method.

Display unshifted amplitude spectrum

The top-right image in Figure 4 is an example of the type of display produced by the code in Listing 9 . This is a plot of the amplitude spectrum without the wavenumber origin being shifted to place it at the center.

(The wavenumber origin is in the top-left corner of the top-right image in Figure 4 .)

This image also shows the result of passing true as the third parameter causing the red axes to be plotted on top of the spectral data.

Listing 9. Display unshifted amplitude spectrum.
new ImgMod29(amplitudeSpect,3,true, displayType);

Questions & Answers

Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
What is specific heat capacity
Destiny Reply
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
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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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