From 0de32f5e112fce2afb66fa73684f256b3115bde1 Mon Sep 17 00:00:00 2001
From: Aaron Fenyes <aaron.fenyes@fareycircles.ooo>
Date: Sun, 31 Aug 2025 11:16:34 +0200
Subject: [PATCH] Measure distortion

---
 app-proto/main.css                      |  4 +++
 app-proto/src/assembly.rs               | 34 ++++++++++++++++++++++++-
 app-proto/src/components/diagnostics.rs | 23 +++++++++++++++++
 3 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/app-proto/main.css b/app-proto/main.css
index a00d309..0ec33e9 100644
--- a/app-proto/main.css
+++ b/app-proto/main.css
@@ -227,6 +227,10 @@ details[open]:has(li) .element-switch::after {
   border-radius: 8px;
 }
 
+#distortion-gauge {
+  margin-top: 8px;
+}
+
 /* display */
 
 #display {
diff --git a/app-proto/src/assembly.rs b/app-proto/src/assembly.rs
index 669c0d0..b5b2bd9 100644
--- a/app-proto/src/assembly.rs
+++ b/app-proto/src/assembly.rs
@@ -3,6 +3,7 @@ use std::{
     cell::Cell,
     cmp::Ordering,
     collections::{BTreeMap, BTreeSet},
+    f64::consts::SQRT_2,
     fmt,
     fmt::{Debug, Formatter},
     hash::{Hash, Hasher},
@@ -122,6 +123,11 @@ pub trait Element: Serial + ProblemPoser + DisplayItem {
     // be used carefully to preserve invariant (1), described in the comment on
     // the `tangent` field of the `Assembly` structure
     fn set_column_index(&self, index: usize);
+    
+    /* KLUDGE */
+    fn has_distortion(&self) -> bool {
+        false
+    }
 }
 
 impl Debug for dyn Element {
@@ -334,6 +340,10 @@ impl Element for Point {
     fn set_column_index(&self, index: usize) {
         self.column_index.set(Some(index));
     }
+    
+    fn has_distortion(&self) -> bool {
+        true
+    }
 }
 
 impl Serial for Point {
@@ -357,6 +367,9 @@ pub trait Regulator: Serial + ProblemPoser + OutlineItem {
     fn subjects(&self) -> Vec<Rc<dyn Element>>;
     fn measurement(&self) -> ReadSignal<f64>;
     fn set_point(&self) -> Signal<SpecifiedValue>;
+    fn distortion(&self) -> Option<ReadSignal<f64>> { /* KLUDGE */
+        None
+    }
 }
 
 impl Hash for dyn Regulator {
@@ -389,6 +402,7 @@ pub struct InversiveDistanceRegulator {
     pub subjects: [Rc<dyn Element>; 2],
     pub measurement: ReadSignal<f64>,
     pub set_point: Signal<SpecifiedValue>,
+    distortion: Option<ReadSignal<f64>>, /* KLUDGE */
     serial: u64,
 }
 
@@ -404,9 +418,23 @@ impl InversiveDistanceRegulator {
         });
         
         let set_point = create_signal(SpecifiedValue::from_empty_spec());
+        let distortion = if subjects.iter().all(|subj| subj.has_distortion()) {
+            Some(create_memo(move || {
+                let set_point_opt = set_point.with(|set_pt| set_pt.value);
+                let measurement_val = measurement.get();
+                match set_point_opt {
+                    None => 0.0,
+                    Some(set_point_val) => SQRT_2 * (
+                        (-set_point_val).sqrt() - (-measurement_val).sqrt()
+                    ).abs(),
+                }
+            }))
+        } else {
+            None
+        };
         let serial = Self::next_serial();
         
-        Self { subjects, measurement, set_point, serial }
+        Self { subjects, measurement, set_point, distortion, serial }
     }
 }
 
@@ -422,6 +450,10 @@ impl Regulator for InversiveDistanceRegulator {
     fn set_point(&self) -> Signal<SpecifiedValue> {
         self.set_point
     }
+    
+    fn distortion(&self) -> Option<ReadSignal<f64>> {
+        self.distortion
+    }
 }
 
 impl Serial for InversiveDistanceRegulator {
diff --git a/app-proto/src/components/diagnostics.rs b/app-proto/src/components/diagnostics.rs
index 51d58f1..ce4a0b4 100644
--- a/app-proto/src/components/diagnostics.rs
+++ b/app-proto/src/components/diagnostics.rs
@@ -111,6 +111,28 @@ fn StepInput() -> View {
     }
 }
 
+#[component]
+fn DistortionGauge() -> View {
+    let state = use_context::<AppState>();
+    let total_distortion = create_memo(move || {
+        state.assembly.regulators.with(|regs| {
+            let mut total = 0.0;
+            for reg in regs {
+                if let Some(distortion) = reg.distortion() {
+                    total += distortion.get();
+                }
+            }
+            total
+        })
+    });
+    
+    view! {
+        div(id = "distortion-gauge") {
+            "Distortion: " (total_distortion.with(|distort| distort.to_string()))
+        }
+    }
+}
+
 fn into_log10_time_point((step, value): (usize, f64)) -> Vec<Option<f64>> {
     vec![
         Some(step as f64),
@@ -315,6 +337,7 @@ pub fn Diagnostics() -> View {
             }
             DiagnosticsPanel(name = "loss") { LossHistory {} }
             DiagnosticsPanel(name = "spectrum") { SpectrumHistory {} }
+            DistortionGauge {}
         }
     }
 }
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