|
| 1 | +{ |
| 2 | + "cells": [ |
| 3 | + { |
| 4 | + "cell_type": "code", |
| 5 | + "execution_count": 6, |
| 6 | + "id": "143dede4", |
| 7 | + "metadata": {}, |
| 8 | + "outputs": [], |
| 9 | + "source": [ |
| 10 | + "import matplotlib.pyplot as plt\n", |
| 11 | + "import numpy as np\n", |
| 12 | + "import quantecon as qe\n", |
| 13 | + "from numpy.linalg import eigvals, solve" |
| 14 | + ] |
| 15 | + }, |
| 16 | + { |
| 17 | + "cell_type": "code", |
| 18 | + "execution_count": 7, |
| 19 | + "id": "0c89899c", |
| 20 | + "metadata": {}, |
| 21 | + "outputs": [], |
| 22 | + "source": [ |
| 23 | + "class AssetPriceModel:\n", |
| 24 | + " \"\"\"\n", |
| 25 | + " A class that stores the primitives of the asset pricing model.\n", |
| 26 | + "\n", |
| 27 | + " Parameters\n", |
| 28 | + " ----------\n", |
| 29 | + " β : scalar, float\n", |
| 30 | + " Discount factor\n", |
| 31 | + " mc : MarkovChain\n", |
| 32 | + " Contains the transition matrix and set of state values for the state\n", |
| 33 | + " process\n", |
| 34 | + " γ : scalar(float)\n", |
| 35 | + " Coefficient of risk aversion\n", |
| 36 | + " g : callable\n", |
| 37 | + " The function mapping states to growth rates\n", |
| 38 | + "\n", |
| 39 | + " \"\"\"\n", |
| 40 | + " def __init__(self, β=0.96, mc=None, γ=2.0, g=np.exp):\n", |
| 41 | + " self.β, self.γ = β, γ\n", |
| 42 | + " self.g = g\n", |
| 43 | + "\n", |
| 44 | + " # A default process for the Markov chain\n", |
| 45 | + " if mc is None:\n", |
| 46 | + " self.ρ = 0.9\n", |
| 47 | + " self.σ = 0.02\n", |
| 48 | + " self.mc = qe.tauchen(n, self.ρ, self.σ)\n", |
| 49 | + " else:\n", |
| 50 | + " self.mc = mc\n", |
| 51 | + "\n", |
| 52 | + " self.n = self.mc.P.shape[0]\n", |
| 53 | + "\n", |
| 54 | + " def test_stability(self, Q):\n", |
| 55 | + " \"\"\"\n", |
| 56 | + " Stability test for a given matrix Q.\n", |
| 57 | + " \"\"\"\n", |
| 58 | + " sr = np.max(np.abs(eigvals(Q)))\n", |
| 59 | + " if not sr < 1 / self.β:\n", |
| 60 | + " msg = f\"Spectral radius condition failed with radius = {sr}\"\n", |
| 61 | + " raise ValueError(msg)\n", |
| 62 | + "\n", |
| 63 | + "\n", |
| 64 | + "def tree_price(ap):\n", |
| 65 | + " \"\"\"\n", |
| 66 | + " Computes the price-dividend ratio of the Lucas tree.\n", |
| 67 | + "\n", |
| 68 | + " Parameters\n", |
| 69 | + " ----------\n", |
| 70 | + " ap: AssetPriceModel\n", |
| 71 | + " An instance of AssetPriceModel containing primitives\n", |
| 72 | + "\n", |
| 73 | + " Returns\n", |
| 74 | + " -------\n", |
| 75 | + " v : array_like(float)\n", |
| 76 | + " Lucas tree price-dividend ratio\n", |
| 77 | + "\n", |
| 78 | + " \"\"\"\n", |
| 79 | + " # Simplify names, set up matrices\n", |
| 80 | + " β, γ, P, y = ap.β, ap.γ, ap.mc.P, ap.mc.state_values\n", |
| 81 | + " J = P * ap.g(y)**(1 - γ)\n", |
| 82 | + "\n", |
| 83 | + " # Make sure that a unique solution exists\n", |
| 84 | + " ap.test_stability(J)\n", |
| 85 | + "\n", |
| 86 | + " # Compute v\n", |
| 87 | + " I = np.identity(ap.n)\n", |
| 88 | + " Ones = np.ones(ap.n)\n", |
| 89 | + " v = solve(I - β * J, β * J @ Ones)\n", |
| 90 | + "\n", |
| 91 | + " return v" |
| 92 | + ] |
| 93 | + }, |
| 94 | + { |
| 95 | + "cell_type": "code", |
| 96 | + "execution_count": 8, |
| 97 | + "id": "00ec6099", |
| 98 | + "metadata": {}, |
| 99 | + "outputs": [], |
| 100 | + "source": [ |
| 101 | + "def consol_price(ap, ζ):\n", |
| 102 | + " \"\"\"\n", |
| 103 | + " Computes price of a consol bond with payoff ζ\n", |
| 104 | + "\n", |
| 105 | + " Parameters\n", |
| 106 | + " ----------\n", |
| 107 | + " ap: AssetPriceModel\n", |
| 108 | + " An instance of AssetPriceModel containing primitives\n", |
| 109 | + "\n", |
| 110 | + " ζ : scalar(float)\n", |
| 111 | + " Coupon of the console\n", |
| 112 | + "\n", |
| 113 | + " Returns\n", |
| 114 | + " -------\n", |
| 115 | + " p : array_like(float)\n", |
| 116 | + " Console bond prices\n", |
| 117 | + "\n", |
| 118 | + " \"\"\"\n", |
| 119 | + " # Simplify names, set up matrices\n", |
| 120 | + " β, γ, P, y = ap.β, ap.γ, ap.mc.P, ap.mc.state_values\n", |
| 121 | + " M = P * ap.g(y)**(- γ)\n", |
| 122 | + "\n", |
| 123 | + " # Make sure that a unique solution exists\n", |
| 124 | + " ap.test_stability(M)\n", |
| 125 | + "\n", |
| 126 | + " # Compute price\n", |
| 127 | + " I = np.identity(ap.n)\n", |
| 128 | + " Ones = np.ones(ap.n)\n", |
| 129 | + " p = solve(I - β * M, β * ζ * M @ Ones)\n", |
| 130 | + "\n", |
| 131 | + " return p" |
| 132 | + ] |
| 133 | + }, |
| 134 | + { |
| 135 | + "cell_type": "code", |
| 136 | + "execution_count": 9, |
| 137 | + "id": "57f42de4", |
| 138 | + "metadata": {}, |
| 139 | + "outputs": [], |
| 140 | + "source": [ |
| 141 | + "def call_option(ap, ζ, p_s, ϵ=1e-7):\n", |
| 142 | + " \"\"\"\n", |
| 143 | + " Computes price of a call option on a consol bond.\n", |
| 144 | + "\n", |
| 145 | + " Parameters\n", |
| 146 | + " ----------\n", |
| 147 | + " ap: AssetPriceModel\n", |
| 148 | + " An instance of AssetPriceModel containing primitives\n", |
| 149 | + "\n", |
| 150 | + " ζ : scalar(float)\n", |
| 151 | + " Coupon of the console\n", |
| 152 | + "\n", |
| 153 | + " p_s : scalar(float)\n", |
| 154 | + " Strike price\n", |
| 155 | + "\n", |
| 156 | + " ϵ : scalar(float), optional(default=1e-8)\n", |
| 157 | + " Tolerance for infinite horizon problem\n", |
| 158 | + "\n", |
| 159 | + " Returns\n", |
| 160 | + " -------\n", |
| 161 | + " w : array_like(float)\n", |
| 162 | + " Infinite horizon call option prices\n", |
| 163 | + "\n", |
| 164 | + " \"\"\"\n", |
| 165 | + " # Simplify names, set up matrices\n", |
| 166 | + " β, γ, P, y = ap.β, ap.γ, ap.mc.P, ap.mc.state_values\n", |
| 167 | + " M = P * ap.g(y)**(- γ)\n", |
| 168 | + "\n", |
| 169 | + " # Make sure that a unique consol price exists\n", |
| 170 | + " ap.test_stability(M)\n", |
| 171 | + "\n", |
| 172 | + " # Compute option price\n", |
| 173 | + " p = consol_price(ap, ζ)\n", |
| 174 | + " w = np.zeros(ap.n)\n", |
| 175 | + " error = ϵ + 1\n", |
| 176 | + " while error > ϵ:\n", |
| 177 | + " # Maximize across columns\n", |
| 178 | + " w_new = np.maximum(β * M @ w, p - p_s)\n", |
| 179 | + " # Find maximal difference of each component and update\n", |
| 180 | + " error = np.amax(np.abs(w - w_new))\n", |
| 181 | + " w = w_new\n", |
| 182 | + "\n", |
| 183 | + " return w" |
| 184 | + ] |
| 185 | + }, |
| 186 | + { |
| 187 | + "cell_type": "code", |
| 188 | + "execution_count": 10, |
| 189 | + "id": "6bc6db6f", |
| 190 | + "metadata": {}, |
| 191 | + "outputs": [], |
| 192 | + "source": [ |
| 193 | + "n = 25\n", |
| 194 | + "ap = AssetPriceModel(β=0.9)\n", |
| 195 | + "ζ = 1.0\n", |
| 196 | + "strike_price = 40\n", |
| 197 | + "\n", |
| 198 | + "x = ap.mc.state_values\n", |
| 199 | + "\n", |
| 200 | + "def timer_function():\n", |
| 201 | + " p = consol_price(ap, ζ)\n", |
| 202 | + " w = call_option(ap, ζ, strike_price)\n", |
| 203 | + "\n", |
| 204 | + "result = qe.timeit(\n", |
| 205 | + " timer_function, runs=1000, verbose=False, \n", |
| 206 | + " results=True, unit=\"milliseconds\"\n", |
| 207 | + " )" |
| 208 | + ] |
| 209 | + }, |
| 210 | + { |
| 211 | + "cell_type": "code", |
| 212 | + "execution_count": 11, |
| 213 | + "id": "d4b6a2e3", |
| 214 | + "metadata": {}, |
| 215 | + "outputs": [ |
| 216 | + { |
| 217 | + "name": "stdout", |
| 218 | + "output_type": "stream", |
| 219 | + "text": [ |
| 220 | + "Results saved to timer_results_numpy.json\n" |
| 221 | + ] |
| 222 | + } |
| 223 | + ], |
| 224 | + "source": [ |
| 225 | + "import json\n", |
| 226 | + "\n", |
| 227 | + "# result is already a dictionary, no need to call _asdict()\n", |
| 228 | + "result_dict = result\n", |
| 229 | + "\n", |
| 230 | + "# Define the filename\n", |
| 231 | + "filename = 'timer_results_numpy.json'\n", |
| 232 | + "\n", |
| 233 | + "# Save the dictionary to a JSON file\n", |
| 234 | + "with open(filename, 'w') as f:\n", |
| 235 | + " json.dump(result_dict, f, indent=4)\n", |
| 236 | + "\n", |
| 237 | + "print(f\"Results saved to {filename}\")" |
| 238 | + ] |
| 239 | + } |
| 240 | + ], |
| 241 | + "metadata": { |
| 242 | + "jupytext": { |
| 243 | + "default_lexer": "ipython" |
| 244 | + }, |
| 245 | + "kernelspec": { |
| 246 | + "display_name": "quantecon", |
| 247 | + "language": "python", |
| 248 | + "name": "python3" |
| 249 | + }, |
| 250 | + "language_info": { |
| 251 | + "codemirror_mode": { |
| 252 | + "name": "ipython", |
| 253 | + "version": 3 |
| 254 | + }, |
| 255 | + "file_extension": ".py", |
| 256 | + "mimetype": "text/x-python", |
| 257 | + "name": "python", |
| 258 | + "nbconvert_exporter": "python", |
| 259 | + "pygments_lexer": "ipython3", |
| 260 | + "version": "3.13.5" |
| 261 | + } |
| 262 | + }, |
| 263 | + "nbformat": 4, |
| 264 | + "nbformat_minor": 5 |
| 265 | +} |
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