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Vansh Verma
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detrendwin

confirmedupstream bugPython · spectrumSystems & data structuresJuly 25, 2026

the question

Does spectrum's speriodogram remove the mean before applying the window?

what came out

spectrum's speriodogram computes |rfft(x*w - m)|^2, subtracting the mean after windowing instead of (x - m)*w. A constant input that should detrend to zero keeps full power (1704 for 5*ones(256)) with a window-shaped DC spike. The fix is to detrend before windowing.

method & receipts

  • Result: confirmed
  • Reproducible — one script re-runs the whole thing from scratch.
  • Tested — a correctness/benchmark suite ships alongside the code.

→ read the code and re-run it

github.com/v-code01/detrendwin