/*
* The point on the Y - axis where the line Y = A + BX intercepts it is given by the equation:
* A = [(SUM(Y))*(SUM(SQUARE(X))) - (SUM(X))*(SUM(X*Y))] / [N*SUM(SQUARE(X)) - SQUARE((SUM(X)))].
*
*
*
* The slope of the line Y = A + BX is given by the equation:
* B = N*SUM(X*Y) - (SUM(X))*(SUM(Y)) / [N*SUM(SQUARE(X)) - SQUARE((SUM(X))]
*
*
*
* The correlation coefficient of the line Y = A + BX where 0 means no correlation and 1 means perfect
* correlation is given by the equation:
* R = N*SUM(X*Y) - (SUM(X))*(SUM(Y)) / SQRT[N*SUM(SQUARE(X)) - SQUARE(SUM(X))]*SQRT[N*SUM(SQUARE(Y)) - SQUARE((SUM(Y)))]
*/
public void Coefficients(out double a, out double b, out double r)
{
double x2sum = ArrayMath.Sum(ArrayMath.Pow(X, 2));
double xsum2 = Math.Pow(ArrayMath.Sum(X), 2);
double ysum = ArrayMath.Sum(Y);
double y2sum = ArrayMath.Sum(ArrayMath.Pow(Y, 2));
double ysum2 = Math.Pow(ArrayMath.Sum(Y), 2);
double xsum = ArrayMath.Sum(X);
double xysum = ArrayMath.Sum(ArrayMath.Multiply(X, Y));
a = (ysum * x2sum - xsum * xysum) / (N * x2sum - xsum2);
b = (N * xysum - xsum * ysum) / (N * x2sum - xsum2);
r = (N * xysum - xsum * ysum) / (Math.Sqrt(N * x2sum - xsum2) * Math.Sqrt(N * y2sum - ysum2));
}
public Complex[] DoFFT(double[] d, WindowBase window)
{
double M = d.Length;
double[] dwindow = window.Calc((int)M);
ArrayMath.Multiply(ref d, ref dwindow);
Complex[] fft = Run(d);
Complex[] spec = new Complex[fft.Length / 2];
for (int i = 1; i < fft.Length / 2 + 1; i++)
{
spec[i - 1].Real = fft[i].Real * 2 / M;
spec[i - 1].Imag = fft[i].Imag * 2 / M;
}
return(spec);
}
