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--- science:social:economics:finance:option-simulator [2025/10/04 07:11] – falsycat
+++ science:social:economics:finance:option-simulator [2025/10/04 15:56] (current) – falsycat
@@ Line 1: / Line 1: @@
-====== Option Price Simulator ======
+====== Option PnL Simulator ======
+[[black-scholes-equation]]に基づいて、オプションの損益をシミュレーションするためのツールです。
+テキストエリアに建玉を入力してCalcボタンを押すと、縦軸を原資産価格、横軸を満期までの日数とした損益のヒートマップを生成することができます。
+建玉の入力記法については[[#how-to-use]]を参照してください。
 <html>
+<style>#heatmap svg { height: auto; }</style>
+<div id="heatmap_param">
+  <div><textarea class="script" style="height: 16rem">SC@22000#5$130
+LC@21750#5$250x2
+SC@21500#5$390</textarea></div>
+  <div style="width: 40rem">
+    <table>
+      <tr><td>IV</td><td><input class="iv" type="number" value="0.2" /></td><td>1=100%</td></tr>
+      <tr><td>Risk-Free rate</td><td><input class="risk-free-rate" type="number" value="0" /></td><td>1=100%</td></tr>
+    </table>
+    <button>Calc</button>
+  </div>
+</div>
 <div id="heatmap"></div>
@@ Line 7: / Line 26: @@
 document.addEventListener("DOMContentLoaded", ()=>{
-// 1. scriptタグを作成
+// error function
-const script = document.createElement('script');
+const erf = (x)=>{
-script.src = "https://cdn.plot.ly/plotly-latest.min.js";
+  const p  =  0.3275911;
-script.async = true;
+  const a1 =  0.254829592;
+  const a2 = -0.284496736;
+  const a3 =  1.421413741;
+  const a4 = -1.453152027;
+  const a5 =  1.061405429;
+  const t = 1 /(1 + p * Math.abs(x));
+  const y = 1 - (((((a5 * t + a4) * t) + a3) * t + a2) * t + a1) * t * Math.exp(-x * x);
+  return (x > 0) ? y : -y;
+};
-// 2. 読み込み完了時の処理
+// Normal Distribution CDF
-script.onload = () => {
+const normCDF = (x)=>(1 + erf(x / Math.sqrt(2))) / 2;
-    console.log('Plotly.js loaded!');
+// formula to calculate option price
+const blackScholes = (S, K, T, r, sigma, type = 'call')=>{
+  // S : 現在の株価
+  // K : 権利行使価格
+  // T : 満期までの時間（年単位）
+  // r : 無リスク金利（年率）
+  // sigma : ボラティリティ（年率）
+  // type : 'call' または 'put'
+  const d1 = (Math.log(S / K) + (r + 0.5 * sigma * sigma) * T) / (sigma * Math.sqrt(T));
+  const d2 = d1 - sigma * Math.sqrt(T);
+  if (type === 'call') {
+      return T>0? S * normCDF(d1) - K * Math.exp(-r * T) * normCDF(d2): Math.max(S-K, 0);
+  } else if (type === 'put') {
+      return T>0? K * Math.exp(-r * T) * normCDF(-d2) - S * normCDF(-d1): Math.max(K-S, 0);
+  } else {
+      throw new Error("invalid type: "+type);
+  }
+};
+// simulation function
+const simulate = (pos, r)=>{
+  const priceMin = Math.min(...pos.map(x => x.strike))*0.8;
+  const priceMax = Math.max(...pos.map(x => x.strike))*1.2;
+  const priceStep = (priceMax - priceMin)/100;
+  let prices = [];
+  for (let S = priceMin; S <= priceMax; S+=priceStep) {
+    prices.push(S);
+  }
+  const dayMax = Math.max(...pos.map(x => x.open_at));
+  let days = [];
+  for (let T = 0; T <= dayMax; ++T) {
+    days.push(T);
+  }
+  let data = [];
+  for (const S of prices) {
+    let row = [];
+    for (const T of days) {
+      let pnl = 0;
+      for (const p of pos) {
+        if (p.open_at >= T) {
+            const open_vol = p.open_price;
+            const curr_vol = blackScholes(S, p.strike, T/252, r, p.iv, p.type);
+            pnl += p.count*(p.side === "short"?
+              open_vol - curr_vol: curr_vol - open_vol);
+        }
+      }
+      row.push(pnl);
+    }
+    data.push(row);
+  }
+  return [days, prices, data];
+};
+// parse
+const parseScript = (script, iv)=>{
+  const tokens = script.split(/\s+/);
+  let pos = [];
+  for (const tok of tokens) {
+    const es = tok.split(/(?=[@$#\^x])/);
+    const p = {};
+    if (es[0] == "LC") {
+      p.side = "long";
+      p.type = "call";
+    } else if (es[0] == "LP") {
+      p.side = "long";
+      p.type = "put";
+    } else if (es[0] == "SC") {
+      p.side = "short";
+      p.type = "call";
+    } else if (es[0] == "SP") {
+      p.side = "short";
+      p.type = "put";
+    } else {
+      throw "fuck";
+    }
+    const get_num = (x)=>+es.filter(s => s.startsWith(x)).at(-1)?.substring(1);
+    p.strike     = get_num("@");
+    p.open_price = get_num("$");
+    p.open_at    = get_num("#");
+    p.iv         = get_num("^") || iv;
+    p.count      = get_num("x") || 1;
+    const valid = p.strike && p.open_price && p.open_at;
+    if (!valid) throw "fuck";
-    // ここでPlotlyを使ったヒートマップ描画などが可能
+    pos.push(p);
-    const data = [{
+  }
-        z: [[1,2],[3,4]],
+  return pos;
-        type: 'heatmap'
-    }];
-    Plotly.newPlot('heatmap', data);
 };
-// 3. bodyに追加してロード開始
+// re-paint plot
+const update = ()=>{
+  const params = document.querySelector("#heatmap_param");
+  const script = params.querySelector(".script").value;
+  const iv = +params.querySelector(".iv").value;
+  const riskfree_rate = +params.querySelector(".risk-free-rate").value;
+  const pos = parseScript(script, iv);
+  const [x, y, z] = simulate(pos, riskfree_rate);
+  Plotly.newPlot('heatmap', [{
+    x: x,
+    y: y,
+    z: z,
+    zmid: 0,
+    colorscale: [
+      [0.0, 'blue'],
+      [0.49, 'lightblue'],
+      [0.5, 'black'],
+      [0.51, 'pink'],
+      [1.0, 'red'],
+    ],
+    type: 'heatmap',
+    hovertemplate: 'Days Left: %{x}<br>Underlying Price: %{y}<br>Option PnL: %{z}<extra></extra>',
+  }], {
+    title: {text: "Option PnL simulation"},
+    xaxis: {
+      title: {text: "Days Left"},
+      autorange: "reversed",
+      fixedrange: true,
+    },
+    yaxis: {
+      title: {text: "Underlying Price"},
+      fixedrange: true,
+    },
+    dragmode: false,
+  });
+};
+// ---- main routine ----
+const script = document.createElement('script');
+script.src = "https://cdn.plot.ly/plotly-3.1.0.min.js";
+script.async = true;
+script.onload = ()=>{
+  document.querySelector("#heatmap_param button").addEventListener("click", update);
+  update();
+};
 document.body.appendChild(script);
@@ Line 30: / Line 191: @@
 </script>
 </html>
+===== How To Use =====
+単体の建玉は以下の記法で記述できます。
+単体の建玉記述を1行ずつ記述することで、複数の建玉を記述することができます。
+<code>
+(S/L)(C/P)@strike#open_at$open_price
+  S/L: Short or Long
+  C/P: Call or Put
+  strike    : strike price
+  open_at   : days left at open
+  open_price: price at open
+</code>
+==== 例 ====
+オプション戦略については[[option-strategy]]を参照。
+=== Short Iron Butterfly ===
+<code>
+SC@21000#30$990
+LC@20000#30$590
+LP@20000#30$620
+SP@19000#30$120
+</code>