fix zero averaging

src/bin/psd.rs

@@ -379,6 +379,14 @@ impl App {
     fn row0(&mut self, ui: &mut Ui) {
         ui.checkbox(&mut self.hold, "Hold")
             .on_hover_text("Stop updating plot\nAcquiusition continues in background");
+        ui.separator();
+        if ui
+            .button("Reset")
+            .on_hover_text("Reset PSD stages and begin anew")
+            .clicked()
+        {
+            self.cmd_send.send(Cmd::Reset).unwrap();
+        }
         ui.add(
             Slider::new(&mut self.repaint, 0.01..=10.0)
                 .text("Repaint")
@@ -387,6 +395,15 @@ impl App {
         )
         .on_hover_text("Request repaint after timeout (seconds)");
         ui.separator();
+        ui.add(
+            Slider::new(&mut self.acq.fs, 1e-3..=1e9)
+                .text("Sample rate")
+                .custom_formatter(|x, _| format!("{:.2e}", x))
+                .suffix(" Hz")
+                .logarithmic(true),
+        )
+        .on_hover_text("Input sample rate");
+        ui.separator();
         ComboBox::from_label("Detrend")
             .selected_text(format!("{:?}", self.acq.detrend))
             .show_ui(ui, |ui| {
@@ -398,54 +415,35 @@ impl App {
             })
             .response
             .on_hover_text("Segment detrending method");
-        ui.separator();
-        ui.add(
-            Slider::new(&mut self.acq.fs, 1e-3..=1e9)
-                .text("Sample rate")
-                .custom_formatter(|x, _| format!("{:.2e}", x))
-                .suffix(" Hz")
-                .logarithmic(true),
-        )
-        .on_hover_text("Input sample rate");
-        ui.separator();
-        if ui
-            .button("Reset")
-            .on_hover_text("Reset PSD stages and begin anew")
-            .clicked()
-        {
-            self.cmd_send.send(Cmd::Reset).unwrap();
-        }
     }
 
     fn row1(&mut self, ui: &mut Ui) {
         ui.add(
-            Slider::new(&mut self.acq.avg_max, 1..=1_000_000.min(self.acq.avg))
-                .text("Averaging limit")
+            Slider::new(&mut self.acq.avg, 1..=1_000_000_000)
+                .text("Averages")
                 .logarithmic(true),
         )
-        .on_hover_text("Averaging limit:\nClip averaging amount to this");
+        .on_hover_text("Target averaging count at the top stage");
         ui.separator();
         ui.add(
-            Slider::new(&mut self.acq.avg, 1..=1_000_000_000)
-                .text("Averages")
+            Slider::new(&mut self.acq.avg_max, 1..=1_000_000.min(self.acq.avg))
+                .text("Averaging limit")
                 .logarithmic(true),
         )
-        .on_hover_text(
-            "Averaging count:\nthe averaging starts as boxcar,\nthen continues exponential",
-        );
+        .on_hover_text("Averaging limit:\nClip averaging at each stage to this\nThe averaging starts as boxcar,\nthen continues exponential");
         ui.separator();
         ui.add(
             Slider::new(&mut self.acq.avg_min, 0..=self.acq.avg_max)
                 .text("Min averages")
                 .logarithmic(true),
         )
         .on_hover_text("Minimum averaging count to\nshow data from a stage");
-        ui.separator();
-        ui.checkbox(&mut self.acq.keep_overlap, "Keep overlap")
-            .on_hover_text("Do not remove low-resolution bins");
     }
 
     fn row2(&mut self, ui: &mut Ui) {
+        ui.checkbox(&mut self.acq.keep_overlap, "Keep overlap")
+            .on_hover_text("Do not remove low-resolution bins");
+        ui.separator();
         ui.checkbox(&mut self.acq.integrate, "Integrate")
             .on_hover_text("Show integrated PSD as linear cumulative sum");
         ui.separator();

src/psd.rs

@@ -222,6 +222,8 @@ impl<const N: usize> PsdStage for Psd<N> {
             // fft in-place
             self.fft.process(&mut c);
 
+            let is_first = self.count == 0;
+
             // normalize and keep for EWMA
             let g = if self.count > self.avg {
                 let g = self.avg as f32 / self.count as f32;
@@ -230,6 +232,8 @@ impl<const N: usize> PsdStage for Psd<N> {
             } else {
                 1.0
             };
+            self.count += 1;
+
             // convert positive frequency spectrum to power and accumulate
             for (c, p) in c[..N / 2 + 1]
                 .iter()
@@ -238,7 +242,7 @@ impl<const N: usize> PsdStage for Psd<N> {
                 *p = g * *p + c.norm_sqr();
             }
 
-            let start = if self.count == 0 {
+            let start = if is_first {
                 // decimate entire segment into lower half, keep overlap later
                 0
             } else {
@@ -258,12 +262,10 @@ impl<const N: usize> PsdStage for Psd<N> {
             y[n..][..yi.len()].copy_from_slice(yi);
             n += yi.len();
 
-            if self.count == 0 {
+            if is_first {
                 // keep overlap after decimating entire segment
                 self.buf.copy_within(N - self.win.overlap..N, 0);
             }
-
-            self.count += 1;
             self.idx = self.win.overlap;
         }
         &mut y[..n]
@@ -482,7 +484,11 @@ impl<const N: usize> PsdCascade<N> {
         let mut b = Vec::with_capacity(self.stages.len());
         let mut decimation = 0;
         let f_pass = 2 * N / 5; // 0.8 Nyquist, floor
-        let full = self.stages.iter().take_while(|s| s.count > 0).count();
+        let full = self
+            .stages
+            .iter()
+            .take_while(|stage| stage.count() >= opts.min_count)
+            .count();
         for (i, stage) in self.stages.iter().enumerate() {
             // a stage yields frequency bins 0..N/2 from DC up to its nyquist
             // 0..floor(0.4*N) is its passband if it was preceeded by a decimator