We are looking to plot to time series accelerometer data as velocity and displacement.
To this end we tried scipy.fftpack.diff, but in looking at the test code  direct_diff() we get odd results, and, why is the doc using "sqrt(-1)*j" in its explanation?
So, I tried  a few different integration methods.

We were first looking at the doc at
http://docs.scipy.org/doc/scipy-0.15.1/reference/generated/scipy.fftpack.diff.html
and code at
https://github.com/scipy/scipy/blob/v0.15.1/scipy/fftpack/pseudo_diffs.py#L26
as well as the tests at
https://github.com/scipy/scipy/blob/master/benchmarks/benchmarks/fftpack_pseudo_diffs.py

The direct_diff() test function in bench_pseudo_diffs.py seems odd, since I have to pass period=-1 to get a matching sign plot for the first integration.
And why the scaling differences required, even for diff() and direct_diff()?
Is my understanding fundamentally flawed?



 Ray