fix stop

js/app.js

@@ -90,6 +90,47 @@ function formatNumber(num) {
     return num.toLocaleString();
 }
 
+// =============================================================================
+// Combination Calculator
+// =============================================================================
+
+function binomial(n, k) {
+    if (k > n) return 0;
+    if (k === 0 || k === n) return 1;
+    let result = 1;
+    for (let i = 0; i < k; i++) {
+        result = result * (n - i) / (i + 1);
+    }
+    return Math.round(result);
+}
+
+function calculateTotalCombinations(numCells, serial, parallel) {
+    const totalNeeded = serial * parallel;
+    if (numCells < totalNeeded) return 0;
+
+    let total = 1;
+    let remaining = numCells;
+
+    for (let i = 0; i < serial; i++) {
+        total *= binomial(remaining, parallel);
+        remaining -= parallel;
+    }
+
+    return total;
+}
+
+function updateMaxIterations() {
+    const serial = parseInt(DOM.cellsSerial.value) || 1;
+    const parallel = parseInt(DOM.cellsParallel.value) || 1;
+    const validCells = AppState.cells.filter(c => c.capacity && c.capacity > 0);
+
+    const totalCombinations = calculateTotalCombinations(validCells.length, serial, parallel);
+
+    // Set max iterations: use total combinations if reasonable, cap at 1,000,000
+    const suggested = Math.min(Math.max(totalCombinations, 1000), 1000000);
+    DOM.maxIterations.value = suggested;
+}
+
 // =============================================================================
 // Configuration Management
 // =============================================================================
@@ -101,6 +142,7 @@ function updateConfigDisplay() {
     DOM.configDisplay.textContent = `${serial}S${parallel}P`;
     DOM.totalCellsNeeded.textContent = total;
     updateMatchingButtonState();
+    updateMaxIterations();
 }
 
 // =============================================================================
@@ -196,6 +238,8 @@ function updateCellStats() {
         ? `${Math.round(capacities.reduce((a, b) => a + b, 0) / capacities.length)} mAh` : '-';
     DOM.statAvgIr.textContent = irs.length > 0
         ? `${(irs.reduce((a, b) => a + b, 0) / irs.length).toFixed(1)} mΩ` : '-';
+
+    updateMaxIterations();
 }
 
 function loadExampleData() {