2016-03-05 17:49:30 -05:00
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###
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# Black-Scholes model functionality for Julia.
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#
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# Designed to be a reference implementation of the Black-Scholes option
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# pricing formula, supporting the original formula and greeks calculation
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###
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using StatsFuns
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"""
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2016-03-05 18:40:26 -05:00
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Calculate the value of \$d_1\$ in the Black-Scholes Formula
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2016-03-05 17:49:30 -05:00
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"""
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2016-03-05 18:40:26 -05:00
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function d1(S, K, σ, r, T, t=0)
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return (log(S./K) + (r + σ.^2/2).*(T-t)) ./ (σ.*sqrt(T-t))
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2016-03-05 17:49:30 -05:00
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end
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2016-03-05 18:40:26 -05:00
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function d2(d1_val, σ, T, t=0)
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2016-03-05 17:49:30 -05:00
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return d1_val - σ .* sqrt(T-t)
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end
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2016-03-05 18:40:26 -05:00
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function blackscholes_call(S, K, σ, r, T, t=0)
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d1_val = d1(S, K, σ, r, T, t)
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2016-03-05 17:49:30 -05:00
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d2_val = d2(d1_val, σ, T, t)
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return normcdf(d1_val) .* S - normcdf(d2_val) .* K .* exp(-r .* (T - t))
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end
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2016-03-05 18:40:26 -05:00
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function blackscholes_put(S, K, σ, r, T, t=0)
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d1_val = d1(S, K, σ, r, T, t)
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2016-03-05 17:49:30 -05:00
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d2_val = d2(d1_val, σ, T, t)
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2016-03-05 18:40:26 -05:00
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return normcdf(-d2_val).*K.*exp(-r.*(T-t)) - normcdf(-d1_val).*S
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2016-03-05 17:49:30 -05:00
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end
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