# 4.1 Java1482-spectrum analysis using java, sampling frequency,  (Page 16/24)

 Page 16 / 24

## Compute the complex energy at each frequency

That is all there is to it. For each frequency of interest, you can use this process to compute a complexnumber, Real(F)-jImag(F), which represents the complex energy corresponding to that frequency in the target time series.

Similarly, you can compute the sum of the squares of the real and imaginary parts and consider that to be a measure of the power at that frequency in thetime series. The square root of the power is the amplitude of the energy at that frequency.

## Nested for loops

Normally we are interested in more than one frequency, so we would repeat the above procedure once for each frequency of interest. This suggests the use ofnested for loops in the algorithm. The outer loop specifies the frequency of interest. The inner loop computes the sum of the products at a particularfrequency.

## Description of the transform method

The static method named transform performs a real to complex Fourier transform. The method does not implement the FFT algorithm. Rather, itimplements a straightforward sampled data version of the continuous Fourier transform defined using integral calculus. (See ForwardRealToComplexFFT01 for an FFT algorithm.)

## The return values

The method returns the following:

• Real part of the spectral analysis result
• Imaginary part of the spectral analysis result
• Magnitude of the spectral analysis result
• Phase angle of the spectral analysis result in degrees

## The transform method parameters

The method parameters are:

• double[] data - incoming real data
• double[] realOut - outgoing real data
• double[] imagOut - outgoing imaginary data
• double[] angleOut - outgoing phase angle in degrees
• double[] magnitude - outgoing amplitude spectrum
• int zero - the index of the incoming data sample that represents zero time
• double lowF - low frequency limit for computation as a fraction of sampling frequency
• double highF - high frequency limit for computation as a fraction of sampling frequency

## Frequency increment, magnitude spectrum, and number of returned values

The computational frequency increment is the difference between the high and low limits divided by the length of the magnitude array.

The magnitude or amplitude is computed as the square root of the sum of the squares of the real and imaginary parts. This value is divided by the incomingdata length, which is given by data.length .

The method returns a number of points in the frequency domain equal to the incoming data length regardless of the high and low frequency limits.

## The beginning of the transform method

The class and the transform method begin in Listing 14 . The code in Listing 14 is described above.

Listing 14. The beginning of the transform method.
```public class ForwardRealToComplex01{ public static void transform(double[] data,double[] realOut,double[] imagOut,double[] angleOut,double[] magnitude,int zero, double lowF,double highF){ double pi = Math.PI;//for convenienceint dataLen = data.length; double delF = (highF-lowF)/data.length;```

anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Got questions? Join the online conversation and get instant answers!