Rename logistic cost labels to cost function wording

logistic-regression/cost-visualization.html

@@ -73,10 +73,10 @@
         <div id="modelDefinition" class="model-definition"></div>
 
         <p class="hint">
-          The height represents Binary Cross-Entropy (BCE) cost J(theta). Lower points correspond to parameter values that better fit class labels.
+          The height represents the cost function J(theta). Lower points correspond to parameter values that better fit class labels.
         </p>
         <p class="hint">
-          Each trajectory point is one gradient-descent update: horizontal movement = parameter changes, vertical movement = BCE change.
+          Each trajectory point is one gradient-descent update: horizontal movement = parameter changes, vertical movement = cost-function change.
         </p>
 
         <div id="landscapeSummary" class="landscape-summary"></div>
@@ -130,6 +130,6 @@
     </main>
 
     <script src="https://cdn.plot.ly/plotly-2.35.2.min.js"></script>
-    <script src="cost.js?v=20260814c"></script>
+    <script src="cost.js?v=20260816a"></script>
   </body>
 </html>

logistic-regression/cost.js

@@ -494,7 +494,7 @@ function buildHover(meta, point) {
     `Iteration: ${point.step}`,
     `${meta.p1Name}: ${point.p1.toFixed(4)}`,
     `${meta.p2Name}: ${point.p2.toFixed(4)}`,
-    `BCE cost: ${point.cost.toFixed(4)}`,
+    `Cost function: ${point.cost.toFixed(4)}`,
   ].join("<br>");
 }
 
@@ -597,9 +597,9 @@ function updateSummary(caseKey) {
 
   if (state.trajectory.length === 0) {
     landscapeSummary.innerHTML = `
-      <span class="landscape-pill">Start BCE: --</span>
-      <span class="landscape-pill">Current BCE: --</span>
-      <span class="landscape-pill">Final BCE: --</span>
+      <span class="landscape-pill">Start cost: --</span>
+      <span class="landscape-pill">Current cost: --</span>
+      <span class="landscape-pill">Final cost: --</span>
       <span class="landscape-pill">Reduction: --</span>
       <span class="landscape-pill">Iterations: 0 / 0</span>
     `;
@@ -613,9 +613,9 @@ function updateSummary(caseKey) {
   const reduction = ((start.cost - final.cost) / Math.max(1e-9, start.cost)) * 100;
 
   landscapeSummary.innerHTML = `
-    <span class="landscape-pill">Start BCE: ${start.cost.toFixed(4)}</span>
-    <span class="landscape-pill">Current BCE: ${current.cost.toFixed(4)}</span>
-    <span class="landscape-pill">Final BCE: ${final.cost.toFixed(4)}</span>
+    <span class="landscape-pill">Start cost: ${start.cost.toFixed(4)}</span>
+    <span class="landscape-pill">Current cost: ${current.cost.toFixed(4)}</span>
+    <span class="landscape-pill">Final cost: ${final.cost.toFixed(4)}</span>
     <span class="landscape-pill">Reduction: ${reduction.toFixed(1)}%</span>
     <span class="landscape-pill">Iterations: ${idx} / ${state.trajectory.length - 1}</span>
     <span class="landscape-pill">${meta.p1Name}: ${current.p1.toFixed(3)}, ${meta.p2Name}: ${current.p2.toFixed(3)}</span>
@@ -665,7 +665,7 @@ function renderStats(caseKey) {
     <span>Model case: ${meta.p1Name}, ${meta.p2Name}</span>
     <span>Samples: ${m}</span>
     <span>Current step: ${idx}</span>
-    <span>BCE: ${current.cost.toFixed(4)}</span>
+    <span>Cost function: ${current.cost.toFixed(4)}</span>
     <span>${meta.p1Label}: ${current.p1.toFixed(4)}</span>
     <span>${meta.p2Label}: ${current.p2.toFixed(4)}</span>
   `;
@@ -709,8 +709,8 @@ function renderLandscape(caseKey, grid) {
       colorscale: "Viridis",
       showscale: showSurface,
       visible: showSurface || showContours,
-      colorbar: { title: "BCE", thickness: 14 },
-      hovertemplate: `${meta.p1Name}: %{x:.4f}<br>${meta.p2Name}: %{y:.4f}<br>BCE: %{z:.4f}<extra></extra>`,
+      colorbar: { title: "Cost function", thickness: 14 },
+      hovertemplate: `${meta.p1Name}: %{x:.4f}<br>${meta.p2Name}: %{y:.4f}<br>Cost function: %{z:.4f}<extra></extra>`,
     });
 
     if (showTrajectory && fullPath.length > 0) {
@@ -811,8 +811,8 @@ function renderLandscape(caseKey, grid) {
     colorscale: "Viridis",
     showscale: showSurface,
     visible: showSurface,
-    colorbar: { title: "BCE", thickness: 14 },
-    hovertemplate: `${meta.p1Name}: %{x:.4f}<br>${meta.p2Name}: %{y:.4f}<br>BCE: %{z:.4f}<extra></extra>`,
+    colorbar: { title: "Cost function", thickness: 14 },
+    hovertemplate: `${meta.p1Name}: %{x:.4f}<br>${meta.p2Name}: %{y:.4f}<br>Cost function: %{z:.4f}<extra></extra>`,
   });
 
   const contour3d = buildContourSegments3D(grid);
@@ -891,7 +891,7 @@ function renderLandscape(caseKey, grid) {
     scene: {
       xaxis: { title: meta.p1Label, range: [grid.p1Min, grid.p1Max], showspikes: false },
       yaxis: { title: meta.p2Label, range: [grid.p2Min, grid.p2Max], showspikes: false },
-      zaxis: { title: "Binary Cross-Entropy J(theta)", range: [grid.min, grid.clipMax], showspikes: false },
+      zaxis: { title: "Cost function J(theta)", range: [grid.min, grid.clipMax], showspikes: false },
       aspectmode: "manual",
       aspectratio: { x: 1.14, y: 1.12, z: 0.82 },
       camera: state.camera3d || cloneCamera(DEFAULT_CAMERA),