[agraham]

You missed attaching the attachment

Originally Posted by klaus

The Tan function should be the ATan2 function

It does use the .NET Math.Atan2 function. It is the same Atan2 function as Basic4ppc uses so the problem must be elsewhere.

ph[i] = Math.Atan2(imag[i], real[i]) * DegPerRad;

In the docs Atan2 is specified as the return value is the angle in the Cartesian plane formed by the x-axis, and a vector starting from the origin, (0,0), and terminating at the point, (x,y). It is an angle, θ, measured in radians, such that -π≤θ≤π, and tan(θ) = y / x, where (x, y) is a point in the Cartesian plane. Observe the following:

For (x, y) in quadrant 1, 0 < θ < π/2.

For (x, y) in quadrant 2, π/2 < θ≤π.

For (x, y) in quadrant 3, -π < θ < -π/2.

For (x, y) in quadrant 4, -π/2 < θ < 0.

Shouldn't we open a new thread for the FFT library ?

I was waiting till we were happy with it and then I was going to do a help before starting a new library thread for it.


EDIT:- Commenting out 'FFTPhase(i)=ATan2(FFTImag(i),FFTReal(i))*RadDeg in the For loop in CalcFFT in your previous example and inserting
FFTPhase() = Fft.ToPhase(FFTReal(), FFTImag()) after the Next looks OK for me. Did you get the order of the parameters of ToPhase correct? I see your graph if I reverse them.