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Note that I deleted much of the code from Listing 2 for brevity. You can view the missing code in Listing 14 near the end of the module.

Compute the complex spectrum

The code in Listing 3 calls the static transform method of the ForwardRealToComplex01 class to compute and save the complex spectrum of the time series shown in the top plot of Figure 1 .

Listing 3. Compute the complex spectrum.
ForwardRealToComplex01.transform(timeDataIn, realSpect,imagSpect, angle,magnitude, zero,0.0, 1.0);

The method parameters

I explained the transform method in the earlier module titled Spectrum Analysis using Java, Sampling Frequency, Folding Frequency, and the FFT Algorithm . The three middle plots in Figure 1 are plots of the data returned in the arrays referred to by realSpect , imagSpect , and magnitude by the transform method.

The angle results returned by the transform program are not used in this module.

One of the parameters (zero) establishes that the first sample in the time series array referred to by timeDataIn represents the zero time origin.

The parameters also specify that the complex spectrum is to be computed at a set of equally spaced frequencies ranging from zero (0.0) to the sampling frequency (1.0) .

Perform the inverse Fourier transform

The code in Listing 4 calls the static inverseTransform method of the InverseComplexToReal01 class to perform an inverse Fourier transform on the complex spectral data, producing the output time series shownin the bottom plot in Figure 1 .

Listing 4. Perform the inverse Fourier transform.
InverseComplexToReal01.inverseTransform( realSpect,imagSpect, timeDataOut);}//end constructor

I will explain the inverseTransform method later.

An object of the class dsp035

Listing 4 also signals the end of the constructor. Once the constructor has completed executing, an object of the Dsp035 class exists. The array objects belonging to the object have been populated with the original timeseries, the complex spectrum of the original time series, and the output time series produced by performing an inverse Fourier transform on that complexspectrum. This data is ready for plotting.

The interface methods

All of the remaining code in Dsp035 consists of the six methods necessary to satisfy the interface named GraphIntfc01 . Those methods are required to provide data to the plotting program, as explainedin earlier modules in this series.

If you have studied the earlier modules in this series, you probably don't want to hear any more about those methods, so I won't discuss them further. Youcan view the six interface methods in Listing 14 near the end of the modules.

The InverseComplexToReal01 class

The static method named inverseTransform performs a complex-to-real inverse discrete Fourier transform returning a real result only.In other words, the method transforms a complex input to a real output.

Questions & Answers

can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
Idrissa Reply
im all ears I need to learn
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what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
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algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
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Rachael Reply
I'm not good at math so would you help me
what is the problem that i will help you to self with?
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
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what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
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what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
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
anybody can imagine what will be happen after 100 years from now in nano tech world
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
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
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how did you get the value of 2000N.What calculations are needed to arrive at it
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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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