diff --git a/app-proto/src/assembly.rs b/app-proto/src/assembly.rs
index 055b9a2..387b567 100644
--- a/app-proto/src/assembly.rs
+++ b/app-proto/src/assembly.rs
@@ -8,7 +8,6 @@ use web_sys::{console, wasm_bindgen::JsValue}; /* DEBUG */
 use crate::{
     engine::{
         Q,
-        change_half_curvature,
         local_unif_to_std,
         realize_gram,
         sphere,
@@ -402,9 +401,37 @@ impl Assembly {
                 let representation = self_for_effect.elements.with_untracked(
                     |elts| elts[subject].representation
                 );
-                representation.update(
-                    |rep| change_half_curvature(rep, half_curv)
-                );
+                representation.update(|rep| {
+                    // set the sphere's half-curvature to the desired value
+                    rep[3] = half_curv;
+                    
+                    // restore normalization by contracting toward the curvature
+                    // axis
+                    const SIZE_THRESHOLD: f64 = 1e-9;
+                    let half_q_lt = -2.0 * half_curv * rep[4];
+                    let half_q_lt_sq = half_q_lt * half_q_lt;
+                    let mut spatial = rep.fixed_rows_mut::<3>(0);
+                    let q_sp = spatial.norm_squared();
+                    if q_sp < SIZE_THRESHOLD && half_q_lt_sq < SIZE_THRESHOLD {
+                        spatial.copy_from_slice(
+                            &[0.0, 0.0, (1.0 - 2.0 * half_q_lt).sqrt()]
+                        );
+                    } else {
+                        let scaling = half_q_lt + (q_sp + half_q_lt_sq).sqrt();
+                        spatial.scale_mut(1.0 / scaling);
+                        rep[4] /= scaling;
+                    }
+                    
+                    /* DEBUG */
+                    // verify normalization
+                    let rep_for_debug = rep.clone();
+                    console::log_1(&JsValue::from(
+                        format!(
+                            "Sphere self-product after curvature change: {}",
+                            rep_for_debug.dot(&(&*Q * &rep_for_debug))
+                        )
+                    ));
+                });
                 self_for_effect.realize();
             }
         });
@@ -422,16 +449,16 @@ impl Assembly {
         
         // set up the constraint problem
         let problem = self.elements.with_untracked(|elts| {
-            let mut problem = ConstraintProblem::new(elts.len());
+            let mut problem_to_be = ConstraintProblem::new(elts.len());
             for (_, elt) in elts {
-                elt.pose(&mut problem, elts);
+                elt.pose(&mut problem_to_be, elts);
             }
             self.regulators.with_untracked(|regs| {
                 for (_, reg) in regs {
-                    reg.pose(&mut problem, elts);
+                    reg.pose(&mut problem_to_be, elts);
                 }
             });
-            problem
+            problem_to_be
         });
         
         /* DEBUG */
diff --git a/app-proto/src/engine.rs b/app-proto/src/engine.rs
index 869a7de..44f44e0 100644
--- a/app-proto/src/engine.rs
+++ b/app-proto/src/engine.rs
@@ -35,40 +35,6 @@ pub fn sphere_with_offset(dir_x: f64, dir_y: f64, dir_z: f64, off: f64, curv: f6
     ])
 }
 
-// given a sphere's representation vector, change the sphere's half-curvature to
-// `half-curv` and then restore normalization by contracting the representation
-// vector toward the curvature axis
-pub fn change_half_curvature(rep: &mut DVector<f64>, half_curv: f64) {
-    // set the sphere's half-curvature to the desired value
-    rep[3] = half_curv;
-    
-    // restore normalization by contracting toward the curvature axis
-    const SIZE_THRESHOLD: f64 = 1e-9;
-    let half_q_lt = -2.0 * half_curv * rep[4];
-    let half_q_lt_sq = half_q_lt * half_q_lt;
-    let mut spatial = rep.fixed_rows_mut::<3>(0);
-    let q_sp = spatial.norm_squared();
-    if q_sp < SIZE_THRESHOLD && half_q_lt_sq < SIZE_THRESHOLD {
-        spatial.copy_from_slice(
-            &[0.0, 0.0, (1.0 - 2.0 * half_q_lt).sqrt()]
-        );
-    } else {
-        let scaling = half_q_lt + (q_sp + half_q_lt_sq).sqrt();
-        spatial.scale_mut(1.0 / scaling);
-        rep[4] /= scaling;
-    }
-    
-    /* DEBUG */
-    // verify normalization
-    let rep_for_debug = rep.clone();
-    console::log_1(&JsValue::from(
-        format!(
-            "Sphere self-product after curvature change: {}",
-            rep_for_debug.dot(&(&*Q * &rep_for_debug))
-        )
-    ));
-}
-
 // --- partial matrices ---
 
 pub struct MatrixEntry {