|
| 1 | +""" |
| 2 | +Author: shifulin |
| 3 | + |
| 4 | +""" |
| 5 | +from math import sqrt, exp, inf |
| 6 | +import numpy as np |
| 7 | + |
| 8 | + |
| 9 | +def _call_price(s, k, sigma, r, t, steps=100): |
| 10 | + r_ = exp(r * (t / steps)) |
| 11 | + r_reciprocal = 1.0 / r_ |
| 12 | + u = exp(sigma * sqrt(t / steps)) |
| 13 | + d = 1.0 / u |
| 14 | + u_square = u ** 2 |
| 15 | + p_u = (r_ - d) / (u - d) |
| 16 | + p_d = 1.0 - p_u |
| 17 | + prices = np.zeros(steps + 1) |
| 18 | + prices[0] = s * d ** steps |
| 19 | + for i in range(1, steps + 1): |
| 20 | + prices[i] = prices[i - 1] * u_square |
| 21 | + values = np.zeros(steps + 1) |
| 22 | + for i in range(steps + 1): |
| 23 | + values[i] = max(0.0, prices[i] - k) |
| 24 | + for j in range(steps, 0, -1): |
| 25 | + for i in range(j): |
| 26 | + values[i] = (p_u * values[i + 1] + p_d * values[i]) * r_reciprocal |
| 27 | + prices[i] = d * prices[i + 1] |
| 28 | + values[i] = max(values[i], prices[i] - k) |
| 29 | + # print(values) |
| 30 | + return values[0] |
| 31 | + |
| 32 | + |
| 33 | +def _put_price(s, k, sigma, r, t, steps=100): |
| 34 | + r_ = exp(r * (t / steps)) |
| 35 | + r_reciprocal = 1.0 / r_ |
| 36 | + u = exp(sigma * sqrt(t / steps)) |
| 37 | + d = 1.0 / u |
| 38 | + u_square = u ** 2 |
| 39 | + p_u = (r_ - d) / (u - d) |
| 40 | + p_d = 1.0 - p_u |
| 41 | + prices = np.zeros(steps + 1) |
| 42 | + prices[0] = s * d ** steps |
| 43 | + for i in range(1, steps + 1): |
| 44 | + prices[i] = prices[i - 1] * u_square |
| 45 | + values = np.zeros(steps + 1) |
| 46 | + for i in range(steps + 1): |
| 47 | + values[i] = max(0, k - prices[i]) |
| 48 | + for j in range(steps, 0, -1): |
| 49 | + for i in range(0, j): |
| 50 | + values[i] = (p_u * values[i + 1] + p_d * values[i]) * r_reciprocal |
| 51 | + prices[i] = d * prices[i + 1] |
| 52 | + values[i] = max(values[i], k - prices[i]) |
| 53 | + return values[0] |
| 54 | + |
| 55 | + |
| 56 | +def call_price(s, k, sigma, r, t, steps=100): |
| 57 | + return (_call_price(s, k, sigma, r, t, steps) + _call_price(s, k, sigma, r, t, steps + 1)) / 2.0 |
| 58 | + |
| 59 | + |
| 60 | +def put_price(s, k, sigma, r, t, steps=100): |
| 61 | + return (_put_price(s, k, sigma, r, t, steps) + _put_price(s, k, sigma, r, t, steps + 1)) / 2.0 |
| 62 | + |
| 63 | + |
| 64 | +def delta(s, k, sigma, r, t, option_type, steps=100): |
| 65 | + if t == 0.0: |
| 66 | + if s == k: |
| 67 | + return {'Call': 0.5, 'Put': -0.5}[option_type] |
| 68 | + elif s > k: |
| 69 | + return {'Call': 1.0, 'Put': 0.0}[option_type] |
| 70 | + else: |
| 71 | + return {'Call': 0.0, 'Put': -1.0}[option_type] |
| 72 | + else: |
| 73 | + price_func = {'Call': call_price, 'Put': put_price}[option_type] |
| 74 | + return (price_func(s + 0.01, k, sigma, r, t, steps=steps) - |
| 75 | + price_func(s - 0.01, k, sigma, r, t, steps=steps)) * 50.0 |
| 76 | + |
| 77 | + |
| 78 | +def gamma(s, k, sigma, r, t, option_type, steps=100): |
| 79 | + if t == 0.0: |
| 80 | + return inf if s == k else 0.0 |
| 81 | + price_func = {'Call': call_price, 'Put': put_price}[option_type] |
| 82 | + return (price_func(s + 0.01, k, sigma, r, t, steps=steps) + |
| 83 | + price_func(s + 0.01, k, sigma, r, t, steps=steps) - |
| 84 | + price_func(s, k, sigma, r, t, steps=steps) * 2.0) * 10000.0 |
| 85 | + |
| 86 | + |
| 87 | +def theta(s, k, sigma, r, t, option_type, steps=100): |
| 88 | + price_func = {'Call': call_price, 'Put': put_price}[option_type] |
| 89 | + t_unit = 1.0 / 365.0 |
| 90 | + if t <= t_unit: |
| 91 | + return price_func(s, k, sigma, r, 0.0001, steps=steps) - \ |
| 92 | + price_func(s, k, sigma, r, t, steps=steps) |
| 93 | + else: |
| 94 | + return price_func(s, k, sigma, r, t - t_unit, steps=steps) - \ |
| 95 | + price_func(s, k, sigma, r, t, steps=steps) |
| 96 | + |
| 97 | + |
| 98 | +def vega(s, k, sigma, r, t, option_type, steps=100): |
| 99 | + price_func = {'Call': call_price, 'Put': put_price}[option_type] |
| 100 | + if sigma < 0.02: |
| 101 | + return 0.0 |
| 102 | + else: |
| 103 | + return (price_func(s, k, sigma + 0.01, r, t, steps=steps) - |
| 104 | + price_func(s, k, sigma - 0.01, r, t, steps=steps)) * 50.0 |
| 105 | + |
| 106 | + |
| 107 | +def rho(s, k, sigma, r, t, option_type, steps=100): |
| 108 | + price_func = {'Call': call_price, 'Put': put_price}[option_type] |
| 109 | + return (price_func(s, k, sigma, r + 0.001, t, steps=steps) - |
| 110 | + price_func(s, k, sigma, r - 0.001, t, steps=steps)) * 500.0 |
| 111 | + |
| 112 | + |
| 113 | +def call_iv(c, s, k, t, r=0.03, sigma_min=0.01, sigma_max=1.0, e=0.00001, steps=100): |
| 114 | + sigma_mid = (sigma_min + sigma_max) / 2.0 |
| 115 | + call_min = call_price(s, k, sigma_min, r, t, steps) |
| 116 | + call_max = call_price(s, k, sigma_max, r, t, steps) |
| 117 | + call_mid = call_price(s, k, sigma_mid, r, t, steps) |
| 118 | + diff = c - call_mid |
| 119 | + if c <= call_min: |
| 120 | + return sigma_min |
| 121 | + elif c >= call_max: |
| 122 | + return sigma_max |
| 123 | + while abs(diff) > e: |
| 124 | + if c > call_mid: |
| 125 | + sigma_min = sigma_mid |
| 126 | + else: |
| 127 | + sigma_max = sigma_mid |
| 128 | + sigma_mid = (sigma_min + sigma_max) / 2.0 |
| 129 | + call_mid = call_price(s, k, sigma_mid, r, t, steps) |
| 130 | + diff = c - call_mid |
| 131 | + # print(sigma_mid) |
| 132 | + return sigma_mid |
| 133 | + |
| 134 | + |
| 135 | +def put_iv(c, s, k, t, r=0.03, sigma_min=0.01, sigma_max=1.0, e=0.00001, steps=100): |
| 136 | + sigma_mid = (sigma_min + sigma_max) / 2.0 |
| 137 | + put_min = put_price(s, k, sigma_min, r, t, steps) |
| 138 | + put_max = put_price(s, k, sigma_max, r, t, steps) |
| 139 | + put_mid = put_price(s, k, sigma_mid, r, t, steps) |
| 140 | + diff = c - put_mid |
| 141 | + if c <= put_min: |
| 142 | + return sigma_min |
| 143 | + elif c >= put_max: |
| 144 | + return sigma_max |
| 145 | + while abs(diff) > e: |
| 146 | + if c > put_mid: |
| 147 | + sigma_min = sigma_mid |
| 148 | + else: |
| 149 | + sigma_max = sigma_mid |
| 150 | + sigma_mid = (sigma_min + sigma_max) / 2.0 |
| 151 | + put_mid = put_price(s, k, sigma_mid, r, t, steps) |
| 152 | + diff = c - put_mid |
| 153 | + return sigma_mid |
| 154 | + |
| 155 | + |
| 156 | +def my_test(): |
| 157 | + import matplotlib.pyplot as plt |
| 158 | + a = np.linspace(1.0 / 365.0, 2, 100) |
| 159 | + yc, yp = [], [] |
| 160 | + for i in a: |
| 161 | + yc.append(vega(6.0, 5.0, 0.25, 0.03, i, option_type='Call', steps=100)) |
| 162 | + yp.append(vega(6.0, 5.0, 0.25, 0.03, i, option_type='Put', steps=100)) |
| 163 | + plt.plot(yc) |
| 164 | + plt.plot(yp) |
| 165 | + plt.show() |
| 166 | + |
| 167 | + |
| 168 | +def my_test2(): |
| 169 | + # print(call_price(5.0, 5.0, 0.1, 0.03, 0.4)) |
| 170 | + # call_price(5.0, 5.0, 0.25, 0.03, 0.4, 99) |
| 171 | + print(call_iv(0.138, 3.046, 3.1, 0.5, r=0.03, sigma_min=0.01, sigma_max=1.0, e=0.00001, steps=100)) |
| 172 | + |
| 173 | + |
| 174 | +if __name__ == '__main__': |
| 175 | + my_test2() |
| 176 | + |
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