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

@@ -534,6 +534,7 @@ pub struct Assembly {
     // realization diagnostics
     pub realization_status: Signal<Result<(), String>>,
     pub descent_history: Signal<DescentHistory>,
+    pub step: Signal<SpecifiedValue>,
 }
 
 impl Assembly {
@@ -547,20 +548,33 @@ 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_realization.elements.track();
-            assembly_for_effect.regulators.with(
+            assembly_for_realization.regulators.with(
                 |regs| for reg in regs {
                     reg.set_point().track();
                 }
             );
-            assembly_for_effect.realization_trigger.track();
+            assembly_for_realization.realization_trigger.track();
-            assembly_for_effect.realize();
+            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 +661,16 @@ 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) {
@@ -696,11 +720,12 @@ 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 +733,15 @@ impl Assembly {
                 // report the realization status
                 self.realization_status.set(Ok(()));
                 
-                // read out the solution
+                // display the last realization step
-                for elt in self.elements.get_clone_untracked() {
+                self.step.set(
-                    elt.representation().update(
+                    if step_cnt > 0 {
-                        |rep| rep.set_column(0, &config.column(elt.column_index().unwrap()))
+                        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 +751,10 @@ 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)));
             },
         }
     }

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_last_step = step_val.is_some_and(
+                |n| state.assembly.descent_history.with_untracked(
+                    |history| n as usize + 1 == history.config.len().max(1)
+                )
+            );
+            if
+                state.selection.with(|sel| sel.len() == 1)
+                && realization_successful
+                && on_last_step
+            {
                 let sel = state.selection.with(
                     |sel| sel.into_iter().next().unwrap().clone()
                 );

app-proto/src/engine.rs

@@ -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