feat: Point coordinate regulators (#118)

Implement regulators for the Euclidean coordinates of `Point` entities, automatically creating all three of them for each added point entity. When such a regulator is set, it freezes the corresponding representation coordinate to the set point. In addition, if all three coordinates of a given `Point` are set, the coradius coordinate (which holds the norm of the point) is frozen as well.

Note that a `PointCoordinateRegulator` must be created with a `Point` as the subject. This commit modifies `HalfCurvatureRegulator` analogously, so that it can only be created with a `Sphere`.
Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Co-committed-by: Glen Whitney <glen@studioinfinity.org>

README.md

@@ -12,11 +12,11 @@ Note that currently this is just the barest beginnings of the project, more of a
 
 ### Implementation goals
 
-* Comfortable, intuitive UI
+* Provide a comfortable, intuitive UI
 
-* Able to run in browser (so implemented in WASM-compatible language)
+* Allow execution in browser (so implemented in WASM-compatible language)
 
-* Produce scalable graphics of 3D diagrams, and maybe STL files (or other fabricatable file format) as well.
+* Produce scalable graphics of 3D diagrams, and maybe STL files (or other fabricatable file format) as well
 
 ## Prototype
 
@@ -24,38 +24,40 @@ The latest prototype is in the folder `app-proto`. It includes both a user inter
 
 ### Install the prerequisites
 
-1. Install [`rustup`](https://rust-lang.github.io/rustup/): the officially recommended Rust toolchain manager
-   - It's available on Ubuntu as a [Snap](https://snapcraft.io/rustup)
-2. Call `rustup default stable` to "download the latest stable release of Rust and set it as your default toolchain"
-   - If you forget, the `rustup` [help system](https://github.com/rust-lang/rustup/blob/d9b3601c3feb2e88cf3f8ca4f7ab4fdad71441fd/src/errors.rs#L109-L112) will remind you
-3. Call `rustup target add wasm32-unknown-unknown` to add the [most generic 32-bit WebAssembly target](https://doc.rust-lang.org/nightly/rustc/platform-support/wasm32-unknown-unknown.html)
-4. Call `cargo install wasm-pack` to install the [WebAssembly toolchain](https://rustwasm.github.io/docs/wasm-pack/)
-5. Call `cargo install trunk` to install the [Trunk](https://trunkrs.dev/) web-build tool
+1. Install [`rustup`](https://rust-lang.github.io/rustup/): the officially recommended Rust toolchain manager.
+   - It's available on Ubuntu as a [Snap](https://snapcraft.io/rustup).
+2. Call `rustup default stable` to "download the latest stable release of Rust and set it as your default toolchain".
+   - If you forget, the `rustup` [help system](https://github.com/rust-lang/rustup/blob/d9b3601c3feb2e88cf3f8ca4f7ab4fdad71441fd/src/errors.rs#L109-L112) will remind you.
+3. Call `rustup target add wasm32-unknown-unknown` to add the [most generic 32-bit WebAssembly target](https://doc.rust-lang.org/nightly/rustc/platform-support/wasm32-unknown-unknown.html).
+4. Call `cargo install wasm-pack` to install the [WebAssembly toolchain](https://rustwasm.github.io/docs/wasm-pack/).
+5. Call `cargo install trunk` to install the [Trunk](https://trunkrs.dev/) web-build tool.
+   - In the future, `trunk` can be updated with the same command. (You may need the `--locked` flag if your ambient version of `rustc` does not match that required by `trunk`.)
 6. Add the `.cargo/bin` folder in your home directory to your executable search path
-   - This lets you call Trunk, and other tools installed by Cargo, without specifying their paths
-   - On POSIX systems, the search path is stored in the `PATH` environment variable
+   - This lets you call Trunk, and other tools installed by Cargo, without specifying their paths.
+   - On POSIX systems, the search path is stored in the `PATH` environment variable.
+   - Alternatively, if you don't want to adjust your `PATH`, you can install `trunk` in another directory `DIR` via `cargo install --root DIR trunk`.
 
 ### Play with the prototype
 
-1. From the `app-proto` folder, call `trunk serve --release` to build and serve the prototype
-   - The crates the prototype depends on will be downloaded and served automatically
-   - For a faster build, at the expense of a much slower prototype, you can call `trunk serve` without the `--release` flag
+1. From the `app-proto` folder, call `trunk serve --release` to build and serve the prototype.
+   - The crates the prototype depends on will be downloaded and served automatically.
+   - For a faster build, at the expense of a much slower prototype, you can call `trunk serve` without the `--release` flag.
    - If you want to stay in the top-level folder, you can call `trunk serve --config app-proto [--release]` from there instead.
-3. In a web browser, visit one of the URLs listed under the message `INFO 📡 server listening at:`
-   - Touching any file in the `app-proto` folder will make Trunk rebuild and live-reload the prototype
-4. Press *ctrl+C* in the shell where Trunk is running to stop serving the prototype
+3. In a web browser, visit one of the URLs listed under the message `INFO 📡 server listening at:`.
+   - Touching any file in the `app-proto` folder will make Trunk rebuild and live-reload the prototype.
+4. Press *ctrl+C* in the shell where Trunk is running to stop serving the prototype.
 
 ### Run the engine on some example problems
 
-1. Use `sh` to run the script `tools/run-examples.sh`
-   - The script is location-independent, so you can do this from anywhere in the dyna3 repository
+1. Use `sh` to run the script `tools/run-examples.sh`.
+   - The script is location-independent, so you can do this from anywhere in the dyna3 repository.
    - The call from the top level of the repository is:
      
      ```bash
      sh tools/run-examples.sh
      ```
-   - For each example problem, the engine will print the value of the loss function at each optimization step
-   - The first example that prints is the same as the Irisawa hexlet example from the Julia version of the engine prototype. If you go into `engine-proto/gram-test`, launch Julia, and then
+   - For each example problem, the engine will print the value of the loss function at each optimization step.
+   - The first example that prints is the same as the Irisawa hexlet example from the Julia version of the engine prototype. If you go into `engine-proto/gram-test`, launch Julia, and then execute
      
      ```julia
      include("irisawa-hexlet.jl")
@@ -64,24 +66,24 @@ The latest prototype is in the folder `app-proto`. It includes both a user inter
      end
      ```
      
-     you should see that it prints basically the same loss history until the last few steps, when the lower default precision of the Rust engine really starts to show
+     you should see that it prints basically the same loss history until the last few steps, when the lower default precision of the Rust engine really starts to show.
 
 ### Run the automated tests
 
-1. Go into the `app-proto` folder
-2. Call `cargo test`
+1. Go into the `app-proto` folder.
+2. Call `cargo test`.
 
 ### Deploy the prototype
 
-1. From the `app-proto` folder, call `trunk build --release`
-   - Building in [release mode](https://doc.rust-lang.org/cargo/reference/profiles.html#release) produces an executable which is smaller and often much faster, but harder to debug and more time-consuming to build
-   - If you want to stay in the top-level folder, you can call `trunk build --config app-proto --release` from there instead
+1. From the `app-proto` folder, call `trunk build --release`.
+   - Building in [release mode](https://doc.rust-lang.org/cargo/reference/profiles.html#release) produces an executable which is smaller and often much faster, but harder to debug and more time-consuming to build.
+   - If you want to stay in the top-level folder, you can call `trunk build --config app-proto --release` from there instead.
 2. Use `sh` to run the packaging script `tools/package-for-deployment.sh`.
-   - The script is location-independent, so you can do this from anywhere in the dyna3 repository
+   - The script is location-independent, so you can do this from anywhere in the dyna3 repository.
    - The call from the top level of the repository is:
      ```bash
      sh tools/package-for-deployment.sh
      ```
-   - This will overwrite or replace the files in `deploy/dyna3`
+   - This will overwrite or replace the files in `deploy/dyna3`.
 3. Put the contents of `deploy/dyna3` in the folder on your server that the prototype will be served from.
-   - To simplify uploading, you might want to combine these files into an archive called `deploy/dyna3.zip`. Git has been set to ignore this path
+   - To simplify uploading, you might want to combine these files into an archive called `deploy/dyna3.zip`. Git has been set to ignore this path.

app-proto/Cargo.lock

@@ -255,6 +255,7 @@ dependencies = [
  "charming",
  "console_error_panic_hook",
  "dyna3",
+ "enum-iterator",
  "itertools",
  "js-sys",
  "lazy_static",
@@ -271,6 +272,26 @@ version = "1.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "60b1af1c220855b6ceac025d3f6ecdd2b7c4894bfe9cd9bda4fbb4bc7c0d4cf0"
 
+[[package]]
+name = "enum-iterator"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4549325971814bda7a44061bf3fe7e487d447cba01e4220a4b454d630d7a016"
+dependencies = [
+ "enum-iterator-derive",
+]
+
+[[package]]
+name = "enum-iterator-derive"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "685adfa4d6f3d765a26bc5dbc936577de9abf756c1feeb3089b01dd395034842"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "equivalent"
 version = "1.0.1"

app-proto/Cargo.toml

@@ -10,6 +10,7 @@ default = ["console_error_panic_hook"]
 dev = []
 
 [dependencies]
+enum-iterator = "2.3.0"
 itertools = "0.13.0"
 js-sys = "0.3.70"
 lazy_static = "1.5.0"

app-proto/main.css

@@ -184,6 +184,7 @@ details[open]:has(li) .element-switch::after {
 
 #diagnostics-bar {
   display: flex;
+  gap: 8px;
 }
 
 #realization-status {
@@ -207,6 +208,14 @@ details[open]:has(li) .element-switch::after {
   content: '⚠';
 }
 
+#step-input > label {
+  padding-right: 4px;
+}
+
+#step-input > input {
+  width: 45px;
+}
+
 .diagnostics-panel {
   margin-top: 10px;
   min-height: 180px;

app-proto/src/assembly.rs

@@ -1,10 +1,11 @@
+use enum_iterator::{all, Sequence};
 use nalgebra::{DMatrix, DVector, DVectorView};
 use std::{
     cell::Cell,
     cmp::Ordering,
     collections::{BTreeMap, BTreeSet},
     fmt,
-    fmt::{Debug, Formatter},
+    fmt::{Debug, Display, Formatter},
     hash::{Hash, Hasher},
     rc::Rc,
     sync::{atomic, atomic::AtomicU64},
@@ -26,6 +27,7 @@ use crate::{
         ConfigSubspace,
         ConstraintProblem,
         DescentHistory,
+        MatrixEntry,
         Realization,
     },
     specified::SpecifiedValue,
@@ -84,6 +86,14 @@ impl Ord for dyn Serial {
     }
 }
 
+// Small helper function to generate consistent errors when there
+// are indexing issues in a ProblemPoser
+fn indexing_error(item: &str, name: &str, actor: &str) -> String {
+    format!(
+        "{item} \"{name}\" must be indexed before {actor} writes problem data"
+    )
+}
+
 pub trait ProblemPoser {
     fn pose(&self, problem: &mut ConstraintProblem);
 }
@@ -125,8 +135,8 @@ pub trait Element: Serial + ProblemPoser + DisplayItem {
 }
 
 impl Debug for dyn Element {
-    fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), fmt::Error> {
-        self.id().fmt(f)
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        Debug::fmt(&self.id(), f)
     }
 }
 
@@ -249,8 +259,7 @@ impl Serial for Sphere {
 impl ProblemPoser for Sphere {
     fn pose(&self, problem: &mut ConstraintProblem) {
         let index = self.column_index().expect(
-            format!("Sphere \"{}\" should be indexed before writing problem data", self.id).as_str()
-        );
+            indexing_error("Sphere", &self.id, "it").as_str());
         problem.gram.push_sym(index, index, 1.0);
         problem.guess.set_column(index, &self.representation.get_clone_untracked());
     }
@@ -269,6 +278,7 @@ pub struct Point {
 
 impl Point {
     const WEIGHT_COMPONENT: usize = 3;
+    const NORM_COMPONENT: usize = 4;
     
     pub fn new(
         id: String,
@@ -303,6 +313,15 @@ impl Element for Point {
         )
     }
 
+    fn default_regulators(self: Rc<Self>) -> Vec<Rc<dyn Regulator>> {
+        all::<Axis>()
+            .map(|axis| {
+                Rc::new(PointCoordinateRegulator::new(self.clone(), axis))
+                    as Rc::<dyn Regulator>
+            })
+            .collect()
+    }
+    
     fn id(&self) -> &String {
         &self.id
     }
@@ -345,8 +364,7 @@ impl Serial for Point {
 impl ProblemPoser for Point {
     fn pose(&self, problem: &mut ConstraintProblem) {
         let index = self.column_index().expect(
-            format!("Point \"{}\" should be indexed before writing problem data", self.id).as_str()
-        );
+            indexing_error("Point", &self.id, "it").as_str());
         problem.gram.push_sym(index, index, 0.0);
         problem.frozen.push(Self::WEIGHT_COMPONENT, index, 0.5);
         problem.guess.set_column(index, &self.representation.get_clone_untracked());
@@ -436,8 +454,8 @@ impl ProblemPoser for InversiveDistanceRegulator {
             if let Some(val) = set_pt.value {
                 let [row, col] = self.subjects.each_ref().map(
                     |subj| subj.column_index().expect(
-                        "Subjects should be indexed before inversive distance regulator writes problem data"
-                    )
+                        indexing_error("Subject", subj.id(),
+                            "inversive distance regulator").as_str())
                 );
                 problem.gram.push_sym(row, col, val);
             }
@@ -446,14 +464,14 @@ impl ProblemPoser for InversiveDistanceRegulator {
 }
 
 pub struct HalfCurvatureRegulator {
-    pub subject: Rc<dyn Element>,
+    pub subject: Rc<Sphere>,
     pub measurement: ReadSignal<f64>,
     pub set_point: Signal<SpecifiedValue>,
     serial: u64,
 }
 
 impl HalfCurvatureRegulator {
-    pub fn new(subject: Rc<dyn Element>) -> Self {
+    pub fn new(subject: Rc<Sphere>) -> Self {
         let measurement = subject.representation().map(
             |rep| rep[Sphere::CURVATURE_COMPONENT]
         );
@@ -490,14 +508,85 @@ impl ProblemPoser for HalfCurvatureRegulator {
         self.set_point.with_untracked(|set_pt| {
             if let Some(val) = set_pt.value {
                 let col = self.subject.column_index().expect(
-                    "Subject should be indexed before half-curvature regulator writes problem data"
-                );
+                    indexing_error("Subject", &self.subject.id,
+                        "half-curvature regulator").as_str());
                 problem.frozen.push(Sphere::CURVATURE_COMPONENT, col, val);
             }
         });
     }
 }
 
+#[derive(Clone, Copy, Sequence)]
+pub enum Axis { X = 0, Y = 1, Z = 2 }
+
+impl Axis {
+    fn name(&self) -> &'static str {
+        match self { Axis::X => "X", Axis::Y => "Y", Axis::Z => "Z" }
+    }
+}
+
+impl Display for Axis {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.name())
+    }
+}
+
+pub struct PointCoordinateRegulator {
+    pub subject: Rc<Point>,
+    pub axis: Axis,
+    pub measurement: ReadSignal<f64>,
+    pub set_point: Signal<SpecifiedValue>,
+    serial: u64
+}
+
+impl PointCoordinateRegulator {
+    pub fn new(subject: Rc<Point>, axis: Axis) -> Self {
+        let measurement = subject.representation().map(
+            move |rep| rep[axis as usize]
+        );
+        let set_point = create_signal(SpecifiedValue::from_empty_spec());
+        Self { subject, axis, measurement, set_point, serial: Self::next_serial() }
+    }
+}
+
+impl Serial for PointCoordinateRegulator {
+    fn serial(&self) -> u64 { self.serial }
+}
+
+impl Regulator for PointCoordinateRegulator {
+    fn subjects(&self) -> Vec<Rc<dyn Element>> { vec![self.subject.clone()] }
+    fn measurement(&self) -> ReadSignal<f64> { self.measurement }
+    fn set_point(&self) -> Signal<SpecifiedValue> { self.set_point }
+}
+
+impl ProblemPoser for PointCoordinateRegulator {
+    fn pose(&self, problem: &mut ConstraintProblem) {
+        self.set_point.with_untracked(|set_pt| {
+            if let Some(val) = set_pt.value {
+                let col = self.subject.column_index().expect(
+                    indexing_error("Subject", &self.subject.id,
+                        "point-coordinate regulator").as_str());
+                problem.frozen.push(self.axis as usize, col, val);
+                // If all three of the subject's spatial coordinates have been
+                // frozen, then freeze its norm component:
+                let mut coords = [0.0; Axis::CARDINALITY];
+                let mut nset: usize = 0;
+                for &MatrixEntry {index, value} in &(problem.frozen) {
+                    if index.1 == col && index.0 < Axis::CARDINALITY {
+                        nset += 1;
+                        coords[index.0] = value
+                    }
+                }
+                if nset == Axis::CARDINALITY {
+                    let [x, y, z] = coords;
+                    problem.frozen.push(
+                        Point::NORM_COMPONENT, col, point(x,y,z)[Point::NORM_COMPONENT]);
+                }
+            }
+        });
+    }
+}
+
 // the velocity is expressed in uniform coordinates
 pub struct ElementMotion<'a> {
     pub element: Rc<dyn Element>,
@@ -534,6 +623,7 @@ pub struct Assembly {
     // realization diagnostics
     pub realization_status: Signal<Result<(), String>>,
     pub descent_history: Signal<DescentHistory>,
+    pub step: Signal<SpecifiedValue>,
 }
 
 impl Assembly {
@@ -547,20 +637,33 @@ impl Assembly {
             realization_trigger: create_signal(()),
             realization_status: create_signal(Ok(())),
             descent_history: create_signal(DescentHistory::new()),
+            step: create_signal(SpecifiedValue::from_empty_spec()),
         };
         
         // realize the assembly whenever the element list, the regulator list,
         // a regulator's set point, or the realization trigger is updated
-        let assembly_for_effect = assembly.clone();
+        let assembly_for_realization = assembly.clone();
         create_effect(move || {
-            assembly_for_effect.elements.track();
-            assembly_for_effect.regulators.with(
+            assembly_for_realization.elements.track();
+            assembly_for_realization.regulators.with(
                 |regs| for reg in regs {
                     reg.set_point().track();
                 }
             );
-            assembly_for_effect.realization_trigger.track();
-            assembly_for_effect.realize();
+            assembly_for_realization.realization_trigger.track();
+            assembly_for_realization.realize();
+        });
+        
+        // load a configuration from the descent history whenever the active
+        // step is updated
+        let assembly_for_step_selection = assembly.clone();
+        create_effect(move || {
+            if let Some(step) = assembly.step.with(|n| n.value) {
+                let config = assembly.descent_history.with_untracked(
+                    |history| history.config[step as usize].clone()
+                );
+                assembly_for_step_selection.load_config(&config)
+            }
         });
         
         assembly
@@ -647,6 +750,16 @@ impl Assembly {
         });
     }
     
+    // --- updating the configuration ---
+    
+    pub fn load_config(&self, config: &DMatrix<f64>) {
+        for elt in self.elements.get_clone_untracked() {
+            elt.representation().update(
+                |rep| rep.set_column(0, &config.column(elt.column_index().unwrap()))
+            );
+        }
+    }
+    
     // --- realization ---
     
     pub fn realize(&self) {
@@ -674,6 +787,7 @@ impl Assembly {
         /* DEBUG */
         // log the Gram matrix
         console_log!("Gram matrix:\n{}", problem.gram);
+        console_log!("Frozen entries:\n{}", problem.frozen);
         
         /* DEBUG */
         // log the initial configuration matrix
@@ -696,11 +810,12 @@ impl Assembly {
             console_log!("Loss: {}", history.scaled_loss.last().unwrap());
         }
         
-        // report the loss history
+        // report the descent history
+        let step_cnt = history.config.len();
         self.descent_history.set(history);
         
         match result {
-            Ok(ConfigNeighborhood { config, nbhd: tangent }) => {
+            Ok(ConfigNeighborhood { nbhd: tangent, .. }) => {
                 /* DEBUG */
                 // report the tangent dimension
                 console_log!("Tangent dimension: {}", tangent.dim());
@@ -708,12 +823,15 @@ impl Assembly {
                 // report the realization status
                 self.realization_status.set(Ok(()));
                 
-                // read out the solution
-                for elt in self.elements.get_clone_untracked() {
-                    elt.representation().update(
-                        |rep| rep.set_column(0, &config.column(elt.column_index().unwrap()))
-                    );
+                // display the last realization step
+                self.step.set(
+                    if step_cnt > 0 {
+                        let last_step = step_cnt - 1;
+                        SpecifiedValue::try_from(last_step.to_string()).unwrap()
+                    } else {
+                        SpecifiedValue::from_empty_spec()
                     }
+                );
                 
                 // save the tangent space
                 self.tangent.set_silent(tangent);
@@ -723,7 +841,10 @@ impl Assembly {
                 // setting the status to has a different type than the
                 // `Err(message)` we received from the match: we're changing the
                 // `Ok` type from `Realization` to `()`
-                self.realization_status.set(Err(message))
+                self.realization_status.set(Err(message));
+                
+                // display the initial guess
+                self.step.set(SpecifiedValue::from(Some(0.0)));
             },
         }
     }
@@ -826,7 +947,8 @@ mod tests {
     use crate::engine;
     
     #[test]
-    #[should_panic(expected = "Sphere \"sphere\" should be indexed before writing problem data")]
+    #[should_panic(expected =
+        "Sphere \"sphere\" must be indexed before it writes problem data")]
     fn unindexed_element_test() {
         let _ = create_root(|| {
             let elt = Sphere::default("sphere".to_string(), 0);
@@ -835,7 +957,8 @@ mod tests {
     }
     
     #[test]
-    #[should_panic(expected = "Subjects should be indexed before inversive distance regulator writes problem data")]
+    #[should_panic(expected = "Subject \"sphere1\" must be indexed before \
+        inversive distance regulator writes problem data")]
     fn unindexed_subject_test_inversive_distance() {
         let _ = create_root(|| {
             let subjects = [0, 1].map(

app-proto/src/components/diagnostics.rs

@@ -7,7 +7,7 @@ use charming::{
 };
 use sycamore::prelude::*;
 
-use crate::AppState;
+use crate::{AppState, specified::SpecifiedValue};
 
 #[derive(Clone)]
 struct DiagnosticsState {
@@ -48,6 +48,69 @@ fn RealizationStatus() -> View {
     }
 }
 
+// history step input
+#[component]
+fn StepInput() -> View {
+    // get the assembly
+    let state = use_context::<AppState>();
+    let assembly = state.assembly;
+    
+    // the `last_step` signal holds the index of the last step
+    let last_step = assembly.descent_history.map(
+        |history| match history.config.len() {
+            0 => None,
+            n => Some(n - 1),
+        }
+    );
+    let input_max = last_step.map(|last| last.unwrap_or(0));
+    
+    // these signals hold the entered step number
+    let value = create_signal(String::new());
+    let value_as_number = create_signal(0.0);
+    
+    create_effect(move || {
+        value.set(assembly.step.with(|n| n.spec.clone()));
+    });
+    
+    view! {
+        div(id = "step-input") {
+            label { "Step" }
+            input(
+                r#type = "number",
+                min = "0",
+                max = input_max.with(|max| max.to_string()),
+                bind:value = value,
+                bind:valueAsNumber = value_as_number,
+                on:change = move |_| {
+                    if last_step.with(|last| last.is_some()) {
+                        // clamp the step within its allowed range. the lower
+                        // bound is redundant on browsers that make it
+                        // impossible to type negative values into a number
+                        // input with a non-negative `min`, but there's no harm
+                        // in being careful
+                        let step_raw = value.with(
+                            |val| SpecifiedValue::try_from(val.clone())
+                                .unwrap_or(SpecifiedValue::from_empty_spec()
+                            )
+                        );
+                        let step = SpecifiedValue::from(
+                            step_raw.value.map(
+                                |val| val.clamp(0.0, input_max.get() as f64)
+                            )
+                        );
+                        
+                        // set the input string and the assembly's active step
+                        value.set(step.spec.clone());
+                        assembly.step.set(step);
+                    } else {
+                        value.set(String::new());
+                    }
+                },
+            )
+        }
+    }
+}
+
 fn into_log10_time_point((step, value): (usize, f64)) -> Vec<Option<f64>> {
     vec![
         Some(step as f64),
@@ -248,6 +311,7 @@ pub fn Diagnostics() -> View {
                     option(value = "loss") { "Loss" }
                     option(value = "spectrum") { "Spectrum" }
                 }
+                StepInput {}
             }
             DiagnosticsPanel(name = "loss") { LossHistory {} }
             DiagnosticsPanel(name = "spectrum") { SpectrumHistory {} }

app-proto/src/components/display.rs

@@ -588,7 +588,25 @@ pub fn Display() -> View {
             location_z *= (time_step * ZOOM_SPEED * zoom).exp();
             
             // manipulate the assembly
-            if state.selection.with(|sel| sel.len() == 1) {
+            /* KLUDGE */
+            // to avoid the complexity of making tangent space projection
+            // conditional and dealing with unnormalized representation vectors,
+            // we only allow manipulation when we're looking at the last step of
+            // a successful realization
+            let realization_successful = state.assembly.realization_status.with(
+                |status| status.is_ok()
+            );
+            let step_val = state.assembly.step.with_untracked(|step| step.value);
+            let on_init_step = step_val.is_some_and(|n| n == 0.0);
+            let on_last_step = step_val.is_some_and(
+                |n| state.assembly.descent_history.with_untracked(
+                    |history| n as usize + 1 == history.config.len().max(1)
+                )
+            );
+            let on_manipulable_step =
+                !realization_successful && on_init_step
+                || realization_successful && on_last_step;
+            if on_manipulable_step && state.selection.with(|sel| sel.len() == 1) {
                 let sel = state.selection.with(
                     |sel| sel.into_iter().next().unwrap().clone()
                 );

app-proto/src/components/outline.rs

@@ -9,6 +9,7 @@ use crate::{
         Element,
         HalfCurvatureRegulator,
         InversiveDistanceRegulator,
+        PointCoordinateRegulator,
         Regulator,
     },
     specified::SpecifiedValue
@@ -119,6 +120,20 @@ impl OutlineItem for HalfCurvatureRegulator {
     }
 }
 
+impl OutlineItem for PointCoordinateRegulator {
+    fn outline_item(self: Rc<Self>, _element: &Rc<dyn Element>) -> View {
+        let name = format!("{} coordinate", self.axis);
+        view! {
+            li(class = "regulator") {
+                div(class = "regulator-label") // for spacing
+                div(class = "regulator-type") { (name) }
+                RegulatorInput(regulator = self)
+                div(class = "status")
+            }
+        }
+    }
+}
+
 // a list item that shows an element in an outline view of an assembly
 #[component(inline_props)]
 fn ElementOutlineItem(element: Rc<dyn Element>) -> View {

app-proto/src/engine.rs

@@ -52,8 +52,8 @@ pub fn project_point_to_normalized(rep: &mut DVector<f64>) {
 // --- partial matrices ---
 
 pub struct MatrixEntry {
-    index: (usize, usize),
-    value: f64,
+    pub index: (usize, usize),
+    pub value: f64,
 }
 
 pub struct PartialMatrix(Vec<MatrixEntry>);
@@ -353,7 +353,7 @@ fn seek_better_config(
 
 // a first-order neighborhood of a configuration
 pub struct ConfigNeighborhood {
-    pub config: DMatrix<f64>,
+    #[cfg(feature = "dev")] pub config: DMatrix<f64>,
     pub nbhd: ConfigSubspace,
 }
 
@@ -388,7 +388,7 @@ pub fn realize_gram(
     if assembly_dim == 0 {
         let result = Ok(
             ConfigNeighborhood {
-                config: guess.clone(),
+                #[cfg(feature = "dev")] config: guess.clone(),
                 nbhd: ConfigSubspace::zero(0),
             }
         );
@@ -509,7 +509,7 @@ pub fn realize_gram(
         // find the kernel of the Hessian. give it the uniform inner product
         let tangent = ConfigSubspace::symmetric_kernel(hess, unif_to_std, assembly_dim);
         
-        Ok(ConfigNeighborhood { config: state.config, nbhd: tangent })
+        Ok(ConfigNeighborhood { #[cfg(feature = "dev")] config: state.config, nbhd: tangent })
     } else {
         Err("Failed to reach target accuracy".to_string())
     };

app-proto/src/specified.rs

@@ -26,6 +26,17 @@ impl SpecifiedValue {
     }
 }
 
+// a `SpecifiedValue` can be constructed from a floating-point option, which is
+// given a canonical specification
+impl From<Option<f64>> for SpecifiedValue {
+    fn from(value: Option<f64>) -> Self {
+        match value {
+            Some(x) => SpecifiedValue{ spec: x.to_string(), value },
+            None => SpecifiedValue::from_empty_spec(),
+        }
+    }
+}
+
 // a `SpecifiedValue` can be constructed from a specification string, formatted
 // as described in the comment on the structure definition. the result is `Ok`
 // if the specification is properly formatted, and `Error` if not