/* This returns an arry of complex numbers. This is not the amplitude of the wave. It must be run through Pythagorus. */
/*
DFTFunc
Purpose:
Forward DFT for a double array of samples of size n. This
converts data in the time domain to the frequency domain. It
returns a complex number array for usage in inverse DFT
funcitons. To properly plot the data returned from this, data
will have to be run through pythagorus.
Parameters:
s: Signal we are changing
n: Size of the signal
*/
public newComplex[] DFTFunc(double[] s, int n)
{
newComplex[] cmplx = new newComplex[n];
double re; /*real*/
double im; /*imaginary*/
for (int f = 0; f < n - 1; f++)
{
re = 0;
im = 0;
for (int t = 0; t < n - 1; t++)
{
re += s[t] * Math.Cos(2 * Math.PI * t * f / n);
im -= s[t] * Math.Sin(2 * Math.PI * t * f / n);
}
cmplx[f] = new newComplex(re, im);
}
return cmplx;
}
/* Preforms the inverse of DFT: this will be displayed to the graph for testing with cosWavCreation */
/*
invDFT
Purpose:
Inverse Descrete Fourier Transform, used to convert from the
frequency domain to the time domain.
Parameters:
A: Complex array to convert
n: Size of the complex array
*/
public double[] invDFT(newComplex[] A, int n)
{
double[] s = new double[n];
double re; /*real*/
double im; /*imaginary*/
for (int t = 0; t < n - 1; t++)
{
re = 0;
im = 0;
for (int f = 0; f < n - 1; f++)
{
re += A[f].getReal() * Math.Cos(2 * Math.PI * t * f / n);
im -= A[f].getImaginary() * Math.Sin(2 * Math.PI * t * f / n);
}
s[t] = (re + im) / n;
}
return s;
}
/*
newDFTFunc
Purpose:
Forward DFT for a double array of samples of size n. This
converts data in the time domain to the frequency domain.
This will perform pythagorus to convert the complex array
directly to usable data for the frequency domain chart.
Parameters:
s: Signal we are changing
n: Size of the signal
*/
public double[] newDFTFunc(double[] s, int n)
{
double[] amplitude = new double[n];
double temp;
newComplex cmplx;
double re; /*real*/
double im; /*imaginary*/
for (int f = 0; f < n - 1; f++)
{
re = 0;
im = 0;
for (int t = 0; t < n - 1; t++)
{
re += s[t] * Math.Cos(2 * Math.PI * t * f / n);
im -= s[t] * Math.Sin(2 * Math.PI * t * f / n);
}
cmplx = new newComplex(re, im);
temp = (cmplx.getReal() * cmplx.getReal()) + (cmplx.getImaginary() * cmplx.getImaginary());
temp = Math.Sqrt(temp);
amplitude[f] = temp; // These are the points we are going to plot.
}
return amplitude;
}
/*
runningDFT
Purpose:
This is the DFT function that will be used with threads. This
will take in the number of threads specified by the user, and
run DFT for that selection on the whole array. This will then
be set to a speccific array for that thread number and used
back in the threadDFT funciton to copy the array to the
array that will be passed back to the windows form.
Parameters:
s: Wave data that will be processed
n: Length of the wave to be processed
threadNum: Current thread being run
maxThreads: Number of threads specified by the user
*/
private void runningDFT(double[] s, int n, int threadNum, int maxThreads)
{
int thNum = threadNum;
double temp;
newComplex cmplx;
double re; //real
double im; //imaginary
int startP = ((n / maxThreads) * (thNum - 1)), endP = ((n / maxThreads) * (thNum));
if(startP < 0)
{
startP = 0;
}
if (thNum == maxThreads - 1)
{
endP = n;
}
for (int f = startP; f < endP; f++) // run through first half
{
re = 0;
im = 0;
for (int t = 0; t < n - 1; t++)
{
re += s[t] * Math.Cos(2 * Math.PI * t * f / n);
im -= s[t] * Math.Sin(2 * Math.PI * t * f / n);
}
cmplx = new newComplex(re, im);
temp = (cmplx.getReal() * cmplx.getReal()) + (cmplx.getImaginary() * cmplx.getImaginary());
temp = Math.Sqrt(temp);
threadAmplitude[f] = temp; // These are the points we are going to plot.
}
}
