FFT is wildly inaccurate for the DC value

[drmpf]

Running the data from Example01_Basic.ino gives
Freq, mag
0, 8288
0.19,817
direct calculation (DFT) gives
0, 66058
0.19, 817.92

matlab gives 10x the results ??
i.e.
0, 660580
0.19, 8180