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src/python_spectrometer/core.py

@@ -135,12 +135,21 @@ class Spectrometer:
         Plot the cumulative data given by
 
         .. math::
-            \int_{f_\mathrm{min}}^f\mathrm{d}f^\prime S(f^\prime)
+            \mathrm{RMS}_S(f)^2 = \int_{f_\mathrm{min}}^f\mathrm{d}
+                f^\prime\,S(f^\prime)
 
-        on a new subplot. :math:`S(f)` is whatever is plotted in the
-        main plot and therefore depends on :attr:`plot_density` and
-        :attr:`plot_amplitude`. Can also be toggled dynamically by
-        setting :attr:`plot_cumulative`.
+        with :math:`\mathrm{RMS}_S(f)` the root-mean-square of the PSD
+        :math:`S(f^\prime)` up to frequency :math:`f^\prime` on a new
+        subplot. If :attr:`plot_density` is False, the spectrum instead
+        of the PSD is used, but note that this does not make a lot of
+        sense.
+
+        If :attr:`plot_dB_scale` is True, the log-ratio of
+        :math:`\mathrm{RMS}_S(f)` with that of the reference data is
+        plotted.
+
+        Can also be toggled dynamically by setting
+        :attr:`plot_cumulative`.
     plot_negative_frequencies : bool, default True
         Plot negative frequencies for two-sided spectra (in case the
         time-series data is complex). For ``matplotlib >= 3.6`` an